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This is PART 1: Introduction and Centers X(1) - X(1000)

Centers X(1001) - X(3000): PART 2
Centers X(3001) - X(5000): PART 3
Centers X(5001) - X(        ): PART 4



Long ago, someone drew a triangle and three segments across it. Each segment started at a vertex and stopped at the midpoint of the opposite side. The segments met in a point. The person was impressed and repeated the experiment on a different shape of triangle. Again the segments met in a point. The person drew yet a third triangle, very carefully, with the same result. He told his friends. To their surprise and delight, the coincidence worked for them, too. Word spread, and the magic of the three segments was regarded as the work of a higher power.

Centuries passed, and someone proved that the three medians do indeed concur in a point, now called the centroid. The ancients found other points, too, now called the incenter, circumcenter and orthocenter. More centuries passed, more special points were discovered, and a definition of triangle center emerged. Like the definition of continuous function, this definition is satisfied by infinitely many objects, of which only finitely many will ever be published. The Encyclopedia of Triangle Centers (ETC) extends a list of 400 triangle centers published in the 1998 book Triangle Centers and Central Triangles. For subsequent developments, click Links (one of the buttons atop this page). In particular, Eric Weisstein's MathWorld, the web's most extensive mathematics resource, covers much of classical and modern triangle geometry, including sketches and references. For an interactive dynamic version of ETC, visit Triangle Centers with C.a.R..

Special points and properties of 4-sided plane figures are closely associated with triangle centers. See Chris van Tienhoven's Encyclopedia of Quadri-Figures (EQF).

Another site in which triangle centers play a central role is Bernard Gibert's Cubics in the Triangle Plane.


NOTATION AND COORDINATES



The reference triangle is ABC, with sidelengths a,b,c. Each triangle center P has homogeneous trilinear coordinates, or simply trilinears, of the form x : y : z. This means there is a nonzero function h of (a,b,c) such that

x = hx', y = hy', z = hz',

where x', y', z' denote the directed distances from P to sidelines BC, CA, AB. Likewise, u : v : w are barycentrics if there is a function k of (a,b,c) such that

u = ku', v = kv', w = kw',

where u', v', w' denote the signed areas of triangles PBC, PCA, PAB. Both coordinate systems are widely used; if trilinears for a point are x : y : z, then barycentrics are ax : by : cz.

In order that every center should have its own name, in cases where no particular name arises from geometrical or historical considerations, the name of a star is used instead. For example, X(770) is POINT ACAMAR. For a list of star names, visit SkyEye - (Un)Common Star Names.

Something new (November 1, 2011): Combos

Suppose that P and U are finite points having normalized barycentric coordinates (p,q,r) and (u,v,w). (Normalized means that p + q + r = 1 and u + v + w = 1.) Suppose that f = f(a,b,c) and g = g(a,b,c) are nonzero homogeneous functions having the same degree of homogeneity. Let x = fp + gu, y = fq + gv, z = fr + gw. The (f,g) combo of P and U, denoted by f*P + g*U, is introduced here as the point X = x : y : z (homogeneous barycentric coordinates); the normalized barycentric coordinates of X are (kx,ky,kz), where k=1/(x+y+z).

Note 1. If P and U are given by normalized trilinear coordinates (instead of barycentric), then f*P + g*U has homogeneous trilinears fp+gu : fq+gv : fr+gw, which is symbolically identical to the homogenous barycentrics for f*P + g*U. The normalized trilinear coordinates for X are (hx,hy,hz), where h=2*area(ABC))/(ax + by + cz).

Note 2. The definition of combo readily extends to finite sets of finite points. In particular, the (f,g,h) combo of P = (p,q,r), U = (u,v,w), J = (j,k,m) is given by fp + gu + hj : fq + gv + hk : fr + gw + hm and denoted by f*P + g*U + h*J.

Note 3. f*P + g*U is collinear with P and U, and its {P,Q}-harmonic conjugate is fp - gu : fq - gv : fr - gw.

Note 4. Suppose that f,g,h are homogeneous symmetric functions all of the same degree of homogeneity, and suppose that X, X', X" are triangle centers. Then f*X + g*X' + h*X'' is a triangle center.

Note 5. Suppose that X, X', X'', X''' are triangle centers and X', X'', X''' are not collinear. Then there exist f,g,h as in Note 4 such that X''' = f*X + g*X' + h*X''. That is, loosely speaking, every triangle center is a linear combination of any other three noncollinear triangle centers.

Note 6. Continuing from Note 5, examples of f,g,h are conveniently given using Conway symbols for a triangle ABC with sidelengths a,b,c. Conway symbols and certain classical symbols are identified here:

S = 2*area(ABC)
SA = (b2 + c2 - a2)/2 = bc cos A
SB = (c2 + a2 - b2)/2 = ca cos B
SC = (a2 + b2 - c2)/2 = ab cos C
s=(a+b+c)/2
sa = (b + c - a)/2
sb = (c + a - b)/2
sc = (a + b - c)/2
r = inradius = S/(a + b + c)
R = circumradius = abc/(2S)
cot(ω) = (a2 + b2 + c2)/(2S), where ω is the Brocard angle

Note 7. The definition of combo along with many examples were developed by Peter Moses prior to November 1, 2011. After that combos have been further developed by Peter Moses, Randy Hutson, and Clark Kimberling.

Examples of two-point combos:
X(175) = 2s*X(1) - (r + 4R)*X(7)
X(176) = 2s*X(1) + (r + 4R)*X(7)
X(481) = s*X(1) - (r + 4R)*X(7)
X(482) = s*X(1) + (r + 4R)*X(7)

Examples of three-point combos: see below at X(1), X(2), etc.

Note 8. Suppose that T is a (central) triangle with vertices A',B',C' given by normalized barycentrics. Then T is represented by a 3x3 matrix with row sums equal to 1. Let NT denote the set of these matrices and let * denote matrix multiplication. Then NT is closed under *. Also, NT is closed under matrix inversion, so that (NT, *) is a group. Once normalized, any central T can be used to produce triangle centers as combos of the form Xcom(nT); see the preambles to X(3663) and X(3739).


HOW TO USE ETC



You won't have to scroll down very far to find well known centers. Other named centers can be found using your computer's searcher - for example, search for "Apollonius" to find "Apollonius point" as X(181).

To determine if a possibly new center is already listed, click Search at the top of this page. If you're unsure of a term, click Glossary. For visual constructions of selected centers with text, click Sketches. To learn about the triangle geometry interest group, Hyacinthos, and other resources, or to view acknowledgments or supplementary encyclopedic material, click Links, Thanks, or Tables.

If you have The Geometer's Sketchpad, you can view sketches of many of the triangle centers. These are dynamic sketches, meaning that you can vary the shape of the reference triangle A, B, C by dragging these vertices. (For information on Sketchpad, click Sketchpad.) The sketches are also useful for making your own Sketchpad tools, so that you can quickly construct X-of-T for many choices of X and T. For example, starting with ABC and point P, you could efficiently construct center X of the four triangles ABC, BCP, CAP, ABP.

The algebraic definition of triangle center (MathWorld) admits points whose geometric interpretation for fixed numerical sidelengths a,b,c is not "central." Roger Smyth offers this example: on the domain of scalene triangles, define f(a,b,c) = 1 for a>b and a>c and f(a,b,c) = 0 otherwise; then f(a,b,c) : f(b,c,a) : f(c,a,b) is a triangle center which picks out the vertex opposite the longest side. Such centers turn out to be useful, as, for example, when distinguishing between the Fermat point and the 1st isogonic center; see the note at X(13).


X(1) = INCENTER

Trilinears       1 : 1 : 1
Barycentrics  a : b : c
Barycentrics  sin A : sin B : sin C
X(1) = 3R*X(2) + r*X(3) + s*cot(ω)*X(6)

X(1) is the point of concurrence of the interior angle bisectors of ABC; the point inside ABC whose distances from sidelines BC, CA, AB are equal. This equal distance, r, is the radius of the incircle, given by

r = 2*area(ABC)/(a + b + c).

Three more points are also equidistant from the sidelines; they are given by these names and trilinears:

A-excenter = -1 : 1 : 1,     B-excenter = 1 : -1 : 1,     C-excenter = 1 : 1 : -1.

The radii of the excircles are

2*area(ABC)/(-a + b + c), 2*area(ABC)/(a - b + c), 2*area(ABC)/(a + b - c).

If you have The Geometer's Sketchpad, you can view Incenter.

Writing the A-exradius as r(a,b,c), the others are r(b,c,a) and r(c,a,b). If these exradii are abbreviated as ra, rb, rc, then 1/r = 1/ra + 1/rb + 1/rc. Moreover,

area(ABC) = sqrt(r*ra*rb*rc) and ra + rb + rc = r + 4R,

where R denotes the radius of the circumcircle.

The incenter is the identity of the group of triangle centers under "trilinear multiplication" defined by

(x : y : z)*(u : v : w) = xu : yv : zw.

A construction for * is easily obtained from the construction for "barycentric multiplication" mentioned in connection with X(2), just below.

The incenter and the other classical centers are discussed in these highly recommended books:

Paul Yiu, Introduction to the Geometry of the Triangle, 2002;
Nathan Altshiller Court, College Geometry, Barnes & Noble, 1952;
Roger A. Johnson, Advanced Euclidean Geometry, Dover, 1960.

Let OA be the circle tangent to side BC at its midpoint and to the circumcircle on the side of BC opposite A. Define OB and OC cyclically. Let LA be the external tangent to circles OB and OC that is nearest to OA. Define LB and LC cyclically. Let A' = LB ∩LC, and define B' and C' cyclically. Then triangle A'B'C' is homothetic to the medial triangle, and the center of homothety is X(1). (See the reference at X(1001)).

X(1) lies on all Z-cubics (e.g., Thomson, Darboux, Napoleon, Neuberg) and these lines:
2,8   3,35   4,33   5,11   6,9   7,20   15,1251   16,1250   19,28   21,31   24,1061   25,1036   29,92   30,79   32,172   39,291   41,101   49,215   54,3460   60,110   61,203   62,202   64,1439   69,1245   71,579   74,3464   75,86   76,350   82,560   84,221   87,192   88,100   90,155   99,741   102,108   104,109   142,277   147,150   159,1486   163,293   164,258   166,1488   167,174   168,173   179,1142   181,970   182,983   184,1726   185,296   188,361   190,537   195,3467   196,207   201,212   204,1712   224,377   227,1465   228,1730   229,267   256,511   257,385   280,1256   281,282   289,363   312,1089   318,1897   320,752   321,964   329,452   335,384   336,811   341,1050   344,1265   346,1219   357,1508   358,1507   364,365   371,1702   372,1703   376,553   378,1063   393,836   394,1711   399,3065   409,1247   410,1248   411,1254   442,1834   474,1339   475,1861   512,875   513,764   514,663   522,1459   528,1086   561,718   563,1820   564,1048   572,604   573,941   574,1571   594,1224   607,949   631,1000   644,1280   647,1021   650,1643   651,1156   659,891   662,897   672,1002   689,719   704,1502   727,932   731,789   748,756   761,825   765,1052   810,1577   840,1308   905,1734   908,998   921,1800   939,1260   945,1875   947,1753   951,1435   969,1444   971,1419   989,1397   1013,1430   1037,1041   1053,1110   1057,1598   1059,1597   1073,3341   1075,1148   1106,1476   1157,3483   1168,1318   1170,1253   1185,1206   1197,1613   1292,1477   1333,1761   1342,1700   1343,1701   1361,1364   1389,1393   1399,1727   1406,1480   1409,1765   1437,1710   1472,1791   1719,1790   1855,1886   1859,1871   1872,1887   2120,3461   2130,3347   3183,3345   3342,3343   3344,3351   3346,3353   3348,3472   3350,3352   3354,3355   3462,3469

X(1) is the {X(2),X(8)}-harmonic conjugate of X(10). For a list of other harmonic conjugates of X(1), click Tables at the top of this page.

X(1) = midpoint of X(I) and X(J) for these (I,J): (7,390), (8,145)

X(1) = reflection of X(I) in X(J) for these (I,J): (2,551), (3,1385), (4,946), (6,1386), (8,10), (9,1001), (10,1125), (11,1387), (36,1319), (40,3), (43,995), (46,56), (57,999), (63,993), (65,942), (72,960), (80,11), (100,214), (191,21), (200,997), (238,1279), (267,229), (291,1015), (355,5), (484,36), (984,37), (1046,58), (1054,106), (1478,226)

X(1) = isogonal conjugate of X(1)
X(1) = isotomic conjugate of X(75)
X(1) = cyclocevian conjugate of X(1029)
X(1) = inverse-in-circumcircle of X(36)
X(1) = inverse-in-Fuhrmann-circle of X(80)
X(1) = inverse-in-Bevan-circle of X(484)
X(1) = complement of X(8)
X(1) = anticomplement of X(10)
X(1) = anticomplementary conjugate of X(1330)
X(1) = complementary conjugate at X(1329)
X(1) = eigencenter of cevian triangle of X(I) for I = 1, 88, 162
X(1) = eigencenter of anticevian triangle of X(I) for I = 1, 44, 513

X(1) = X(I)-Ceva conjugate of X(J) for these (I,J):
(2,9), (4,46), (6,43), (7,57), (8,40), (9,165), (10,191), (21,3), (29,4), (75,63), (77,223), (78,1490), (80,484), (81,6), (82,31), (85,169), (86,2), (88,44), (92,19), (100,513), (104,36), (105,238), (174,173), (188,164), (220,170), (259,503), (266,361), (280,84), (366,364), (508,362), (1492,1491)

X(1) = cevapoint of X(I) and X(J) for these (I,J):
(2,192), (6,55), (11,523), (15,202), (16,203), (19,204), (31,48), (34,207), (37,42), (50,215), (56,221), (65,73), (78,1490), (244,513)

X(1) = X(I)-cross conjugate of X(J) for these (I,J):
(2,87), (3,90), (6,57), (31,19), (33,282), (37,2), (38,75), (42,6), (44,88), (48,63), (55,9), (56,84), (58,267), (65,4), (73,3), (192,43), (207,1490), (221,40), (244,513), (259,258), (266,505), (354,7), (367,366), (500,35), (513,100), (517,80), (518,291), (1491,1492)

X(1) = crosspoint of X(I) and X(J) for these (I,J):
(2,7), (8,280), (21,29), (59,110), (75,92), (81,86)

X(1) = crosssum of X(I) and X(J) for these (I,J):
(2,192), (4,1148), (6,55), (11,523), (15,202), (16,203), (19,204), (31,48), (34,207), (37,42), (44,678), (50,215), (56,221), (57,1419), (65,73), (207,1490), (214,758), (244,513), (500,942), (512,1015), (774,820), (999,1480)

X(1) = crossdifference of any two points on line X(44)X(513)

X(1) = X(I)-Hirst inverse of X(J) for these (I,J):
(2,239), (4,243), (6,238), (9,518), (19,240), (57,241), (105,294), (291,292).

X(1) = X(6)-line conjugate of X(44)

X(1) = X(I)-aleph conjugate of X(J) for these (I,J):
(1,1), (2,63), (4,920), (21,411), (29,412), (88,88), (100,100), (162,162), (174,57), (188,40), (190,190), (266,978), (365,43), (366,9), (507,173), (508,169), (513,1052), (651, 651), (653,653), (655,655), (658,658), (660,660), (662,662), (673,673), (771,771), (799,799), (823,823), (897,897)

X(1) = X(I)-beth conjugate of X(J) for these (I,J):
(1,56), (2,948), (8,8), (9,45), (21,1), (29,34), (55,869), (99,85), (100,1), (110,603), (162,208), (643,1), (644,1), (663,875), (664,1), (1043,78)


X(2) = CENTROID

Trilinears       1/a : 1/b : 1/c
                        = bc : ca : ab
                        = csc A : csc B : csc C
                        = cos A + cos B cos C : cos B + cos C cos A : cos C + cos A cos B
                        = sec A + sec B sec C : sec B + sec C sec A : sec C + sec A sec B
                        = cos A + cos(B - C) : cos B + cos(C - A) : cos C + cos(A - B)
                        = cos B cos C - cos(B - C) : cos C cos A - cos(C - A) : cos A cos B - cos(A - B)

Barycentrics  1 : 1 : 1

X(2) is the point of concurrence of the medians of ABC, situated 1/3 of the distance from each vertex to the midpoint of the opposite side. More generally, if L is any line in the plane of ABC, then the distance from X(2) to L is the average of the distances from A, B, C to L. An idealized triangular sheet balances atop a pin head located at X(2) and also balances atop any knife-edge that passes through X(2). The triangles BXC, CXA, AXB have equal areas if and only if X = X(2).

If you have The Geometer's Sketchpad, you can view Centroid.

X(2) is the centroid of the set of 3 vertices, the centroid of the triangle including its interior, but not the centroid of the triangle without its interior; that centroid is X(10).

X(2) is the identity of the group of triangle centers under "barycentric multiplication" defined by

(x : y : z)*(u : v : w) = xu : yv : zw.

X(2) lies on the Thomson cubic and these lines:
1,8   3,4   6,69   7,9   11,55   12,56   13,16   14,15   17,62   18,61   19,534   31,171   32,83   33,1040   34,1038   35,1479   36,535  37,75   38,244   39,76   40,946   44,89   45,88   51,262   52,1216   54,68   58,540   65,959   66,206   71,1246   72,942   74,113   77,189   80,214   85,241   92,273   94,300   95,97   98,110   99,111   101,116   102,117   103,118   104,119   106,121   107,122   108,123   109,124   112,127   128,1141   129,1298   130,1303   131,1300   133,1294   136,925   137,930   154,1503   165,516   169,1763   174,236   176,1659   178,188   187,316   196,653   201,1393   210,354   216,232   220,1170   222,651   231,1273   242,1851   243,1857   252,1166   253,1073   254,847   257,1432   261,593   265,1511   271,1034   272,284   280,318   283,580   290,327   292,334   294,949   308,702   311,570   314,941   319,1100   322,1108   330,1107   341,1219   351,804   355,944   360,1115   366,367   371,486   372,485   392,517   476,842   480,1223   489,1132   490,1131   495,956   496,1058   514,1022   523,1649   525,1640   561,716   568,1154   572,1746   573,1730   578,1092   585,1336   586,1123   588,1504   589,1505   594,1255   647,850   648,1494   650,693   664,1121   668,1015   670,1084   689,733   743,789   799,873   812,1635   846,1054   914,1442   918,1638   927,1566   954,1260   1073,1249   968,1738   1000,1145   1043,1834   1060,1870   1074,1785   1076,1838   1089,1224   1093,1217   1124,1378   1143,1489   1155,1836   1171,1509   1186,1207   1257,1265   1284,1403   1335,1377   1340,1349   1341,1348   1500,1574   1501,1691   1672,1681   1673,1680   1674,1679   1675,1678   1697,1706   3343,3344   3349,3350   3351,3352

X(2) is the {X(3),X(5)}-harmonic conjugate of X(4). For a list of other harmonic conjugates of X(2), click Tables at the top of this page.

X(2) = midpoint of X(I) and X(J) for these (I,J): (3,381), (4,376), (210,354), (668,3227), (670,3228)
X(2) = reflection of X(I) in X(J) for these (I,J): (1,551), (3,549), (4,381), (5,547), (6,597), (20,376), (69,599), (148,671), (376,3), (381,5), (549,140), (551,1125), (599,141), (671,115), (903,1086), (1121,1146)

X(2) = isogonal conjugate of X(6)
X(2) = isotomic conjugate of X(2)
X(2) = cyclocevian conjugate of X(4)
X(2) = inverse-in-circumcircle of X(23)
X(2) = inverse-in-nine-point-circle of X(858)
X(2) = inverse-in-Brocard-circle of X(110)
X(2) = complement of X(2)
X(2) = anticomplement of X(2)
X(2) = anticomplementary conjugate of X(69)
X(2) = complementary conjugate of X(141)

X(2) = X(I)-Ceva conjugate of X(J) for these (I,J):
(1,192), (4,193), (6,194), (7,145), (8,144), (30,1494), (69,20), (75,8), (76,69), (83,6), (85,7), (86,1), (87,330), (95,3), (98,385), (99,523), (190,514), (264,4), (274,75), (276, 264), (287,401), (290,511), (308,76), (312,329), (325,147), (333,63), (348,347), (491,487), (492,488), (523,148), (626,1502)

X(2) = cevapoint of X(I) and X(J) for these (I,J):
(1,9), (3,6), (5,216), (10,37), (32,206), (39,141), (44,214), (57,223), (114,230), (115,523), (128,231), (132,232), (140,233), (188,236)

X(2) = X(I)-cross conjugate of X(J) for these (I,J):
(1,7), (3,69), (4,253), (5,264), (6,4), (9,8), (10,75), (32,66), (37,1), (39,6), (44,80), (57,189), (75,330), (114,325), (140,95), (141,76), (142,85), (178,508), (187,67), (206,315), (214,320), (216,3), (223,329), (226,92), (230,98), (233,5), (281,280), (395,14), (396,13), (440,306), (511,290), (514,190), (523,99)

X(2) = crosspoint of X(I) and X(J) for these (I,J):
(1,87), (75,85), (76,264), (83,308), (86,274), (95,276)

X(2) = crosssum of X(I) and X(J) for these (I,J):
(1,43), (2,194), (31,41), (32,184), (42,213), (51,217), (125,826), (649,1015), (688,1084), (902,1017), (1400,1409)

X(2) = crossdifference of any two points on line X(187)X(237)

X(2) = X(I)-Hirst inverse of X(J) for these (I,J):
(1,239), (3,401), (4,297), (6,385), (21,448), (27,447), (69,325), (75,350), (98,287), (115,148), (193,230), (291,335), (298,299), (449,452)

X(2) = X(3)-line conjugate of X(237) = X(316)-line conjugate of X(187)

X(2) = X(I)-aleph conjugate of X(J) for these (I,J):
(1,1045), (2,191), (86,2), (174,1046), (333,20), (366,846)

X(2) = X(I)-beth conjugate of X(J) for these (I,J):
(2,57), (21,995) (190,2), (312,312), (333,2), (643,55), (645,2), (646,2), (648,196), (662,222)

X(2) is the unique point X (as a function of a,b,c) for which the vector-sum XA + XB + XC is the zero vector.


X(3) = CIRCUMCENTER

Trilinears       cos A : cos B : cos C
                        = a(b2 + c2 - a2) : b(c2 + a2 - b2) : c(a2 + b2 - c2)

Barycentrics  sin 2A : sin 2B : sin 2C

X(3) is the point of concurrence of the perpendicular bisectors of the sides of ABC. The lengths of segments AX, BX, CX are equal if and only if X = X(3). This common distance is the radius of the circumcircle, which passes through vertices A,B,C. Called the circumradius, it is given by

R = a/(2 sin A) = abc/(4*area(ABC)).

If you have The Geometer's Sketchpad, you can view Circumcenter.

X(3) lies on the Thomson cubic, the Darboux cubic, the Napoleon cubic, the Neuberg cubic, and these lines:
1,35   2,4   6,15   7,943   8,100   9,84   10,197   11,499   12,498   13,17   14,18   19,1871   31,601   33,1753   34,1465   37,975   38,976   41,218   42,967   47,1399   48,71   49,155   54,97   60,1175   63,72   64,154   66,141   67,542  68,343   69,332   73,212   74,110   76,98   77,1410   83,262   86,1246   90,1898   95,264   101,103   102,109   105,277   106,1293   107,1294   108,1295   111,1296   112,1297   113,122   114,127   119,123   125,131   128,1601   142,516   143,1173   145,1483   149,1484   158,243   161,1209   169,910   191,1768   193,1353   194,385   200,963   201,1807   207,1767   223,1035   225,1074   227,1455   238,978   252,930   256,987   269,939   296,820   298,617   299,616   302,621   303,622   305,1799   315,325   345,1791   347,1119   348,1565   352,353   388,495   390,1058   393,1217   395,398   396,397   476,477   485,590   486,615   489,492   490,491   496,497   525,878   595,995   611,1469   613,1428   618,635   619,636   623,629   624,630   639,641   640,642   653,1148   662,1098   667,1083   691,842   695,1613   847,925   901,953   902,1201   917,1305   920,1858   934,972   945,1457   950,1210   951,1407   955,1170   960,997   962,1621   1000,1476   1033,1249   1037,1066   1054,1283   1055,1334   1057,1450   1093,1105   1167,1413   1177,1576   1180,1627   1184,1194   1196,1611   1298,1303   1331,1797   1364,1795   1397,1682   1398,1870   1406,1464   1411,1772   1427,1448   1452,1905   1728,1864   1737,1837   1770,1836   1779,1780   2120,3463   2130,3348   2131,3355   3341,3352   3354,3472   3460,3469   3464,3466

X(3) is the {X(2),X(4)}-harmonic conjugate of X(5). For a list of other harmonic conjugates of X(3), click Tables at the top of this page. If triangle ABC is acute, then X(3) is the incenter of the tangential triangle and the Bevan point, X(40), of the orthic triangle.

X(3) = midpoint of X(I) and X(J) for these (I,J):
(1,40), (2,376), (4,20), (22,378), (74,110), (98,99), (100,104), (101,103), (102,109), (476,477)

X(3) = reflection of X(I) in X(J) for these (I,J):
(1,1385), (2,549), (4,5), (5,140), (6,182), (20,550), (52,389), (110,1511), (114,620), (145,1483), (149,1484), (155,1147), (193,1353), (195,54), (265,125), (355,10), (381,2), (382,4), (399,110), (550,548), (576,575), (946,1125), (1351,6), (1352,141), (1482,1)

X(3) = isogonal conjugate of X(4)
X(3) = isotomic conjugate of X(264)
X(3) = inverse-in-nine-point-circle of X(2072)
X(3) = inverse-in-orthocentroidal-circle of X(5)
X(3) = inverse-in-1st-Lemoine-circle of X(2456)
X(3) = inverse-in-2nd-Lemoine-circle of X(1570)
X(3) = complement of X(4)
X(3) = anticomplement of X(5)
X(3) = complementary conjugate of X(5)
X(3) = anticomplementary conjugate of X(2888)
X(3) = eigencenter of the medial triangle
X(3) = eigencenter of the tangential triangle

X(3) = X(I)-Ceva conjugate of X(J) for these (I,J):
(2,6), (4,155), (5,195), (20,1498), (21,1), (22,159), (30,399), (63,219), (69,394), (77,222), (95,2), (96,68), (99,525), (100,521), (110,520), (250, 110), (283,255)

X(3) = cevapoint of X(I) and X(J) for these (I,J):
(6,154), (48,212), (55,198), (71,228), (185,417), (216,418)

X(3) = X(I)-cross conjugate of X(J) for these (I,J):
(48,222), (55,268), (71,63), (73,1), (184,6), (185,4), (212,219), (216,2), (228,48), (520,110)

X(3) = crosspoint of X(I) and X(J) for these (I,J):
(1,90), (2,69), (4,254), (21,283), (54,96), (59,100), (63,77), (78,271), (81,272), (95,97), (99,249), (110,250), (485,486)

X(3) = crosssum of X(I) and X(J) for these (I,J):
(1,46), (2,193), (3,155), (5,52), (6,25), (11,513), (19,33), (30,113), (37,209), (39, 211), (51,53), (65,225), (114,511), (115,512), (116,514), (117, 515), (118,516), (119,517), (120,518), (121,519), (122,520), (123,521), (124,522), (125,523), (126,524), (127,525), (128,1154), (136,924), (184,571), (185,235), (371,372), (487,488)

X(3) = crossdifference of any two points on line X(230)X(231)
X(3) = X(I)-Hirst inverse of X(J) for these (I,J): (2, 401), (4,450), (6,511), (21,416), (194, 385)
X(3) = X(2)-line conjugate of X(468)

X(3) = X(I)-aleph conjugate of X(J) for these (I,J): (1,1046), (21,3), (188,191), (259,1045)

X(3) = X(I)-beth conjugate of X(J) for these (I,J):
(3,603), (8,355), (21,56), (78,78), (100,3), (110,221), (271,84), (283,3), (333,379), (643,8)


X(4) = ORTHOCENTER

Trilinears       sec A : sec B : sec C
                        = cos A - sin B sin C : cos B - sin C sin A : cos C - sin A sinB
                        = cos A - cos(B - C) : cos B - cos(C - A) : cos C - cos(A - B)
                        = sin B sin C - cos(B - C) : sin C sin A - cos(C - A) : sin A sin B - cos(A - B)

Barycentrics  tan A : tan B : tan C

X(4) is the point of concurrence of the altitudes of ABC.

If you have The Geometer's Sketchpad, you can view Orthocenter.

X(4) and the vertices A,B,C comprise an orthocentric system, defined as a set of four points, one of which is the orthocenter of the triangle of the other three (so that each is the orthocenter of the other three). The incenter and excenters also form an orthocentric system. If ABC is acute, then X(4) is the incenter of the orthic triangle.

Suppose P is not on a sideline of ABC. Let A'B'C' be the cevian triangle of P. Let D,E,F be the circles having diameters AA', BB',CC'. The radical center of D,E,F is X(4). (Floor van Lamoen, Hyacinthos #214, Jan. 24, 2000.)

Ross Honsberger, Episodes in Nineteenth and Twentieth Century Euclidean Geometry, Mathematical Association of America, 1995. Chapter 2: The Orthocenter.

X(4) lies on the Thomson cubic, the Darboux cubic, the Napoleon cubic, the Neuberg cubic, and these lines:
1,33   2,3   6,53   7,273   8,72   9,10   11,56   12,55   13,61   14,62   15,17   16,18   32,98   35,498   36,499   37,1841   39,232   42,1860   46,90   48,1881   49,156   51,185   52,68   54,184   57,84   64,1853   65,158   67,338   69,76   74,107   78,908   79,1784   80,1825   83,182   93,562  94,143   96,231   99,114   100,119   101,118   102,124   103,116   109,117   110,113   111,1560   120,1292   121,1293   122,1294   123,1295   126,1296   127,1289   128,930   129,1303   130,1298   131,135   137,933   141,1350   145,149   147,148   150,152   155,254   162,270   165,1698   171,601   193,1351   195,399   204,1453   218,294   238,602   240,256   250,1553   252,1487   276,327   279,1565   282,3351   371,485   372,486   390,495   394,1217   477,1304   484,3483   487,489   488,490   496,999   512,879   523,1552   542,576   569,1179   572,1474   574,1506   575,598   579,1713   580,1714   590,1151   608,1518   615,1152   616,627   617,628   653,1156   774,1254   801,1092   842,935   937,1534   940,1396   941,1880   953,1309   1036,1065   1037,1067   1038,1076   1039,1096   1040,1074   1073,3350   1138,2132   1157,3482   1160,1162   1161,1163   1251,1832   1329,1376   1340,1348   1341,1349   1385,1538   1430,1468   1499,1550   1715,1730   1716,1721   1717,1718   1726,1782   3065,3464   3347,3472   3348,3355

X(4) is the {X(3),X(5)}-harmonic conjugate of X(2). For a list of other harmonic conjugates of X(4), click Tables at the top of this page.

X(4) = midpoint of X(I) and X(J) for these (I,J): (3,382), (146,3448), (147,148), (149,153), (150,152)

X(4) = reflection of X(I) in X(J) for these (I,J): (1,946), (2,381), (3,5), (5,546), (8,355), (20,3), (24,235), (25,1596), (40,10), (69,1352), (74,125), (98,115), (99,114), (100,119), (101,118), (102,124), (103,116), (104,11), (107,133), (109,117), (110,113), (112,132), (145,1482), (185,389), (186,403), (193,1351), (376,2), (378,427), (550,140), (925,131), (930,128), (944,1), (1113,1312), (1114,1313), (1141,137), (1292,120), (1293,121), (1294,122), (1295,123), (1296,126), (1297,127), (1298,130), (1299,135), (1300,136), (1303, 129), (1350,141), (1593,1595)

X(4) = isogonal conjugate of X(3)
X(4) = isotomic conjugate of X(69)
X(4) = cyclocevian conjugate of X(2)
X(4) = inverse-in-circumcircle of X(186)
X(4) = inverse-in-nine-point-circle of X(403)
X(4) = complement of X(20)
X(4) = anticomplement of X(3)
X(4) = complementary conjugate of X(2883)
X(4) = anticomplementary conjugate of X(20)
X(4) = eigencenter of cevian triangle of X(I) for I = 1, 88, 162
X(4) = eigencenter of anticevian triangle of X(I) for I = 1, 44, 513

X(4) = X(I)-Ceva conjugate of X(J) for these (I,J):
(7,196), (27,19), (29,1), (92,281), (107,523), (264,2), (273,278), (275,6), (286,92), (393, 459)

X(4) = cevapoint of X(I) and X(J) for these (I,J):
(1,46), (2,193), (3,155), (5,52), (6,25), (11,513), (19,33), (30,113), (34,208), (37,209), (39,211), (51,53), (65,225), (114,511), (115,512), (116,514), (117,515), (118,516), (119,517), (120,518), (121,519), (122,520), (123,521), (124,522), (125,523), (126,524), (127,525), (185,235), (371,372), (487,488)

X(4) = X(I)-cross conjugate of X(J) for these (I,J):
(3,254), (6,2), (19,278), (25,393), (33,281), (51,6), (52,24), (65,1), (113,403), (125,523), (185,3), (193,459), (225,158), (389,54), (397,17), (398,18), (407,225), (427,264), (512,112), (513,108), (523,107)

X(4) = crosspoint of X(I) and X(J) for these (I,J): (2,253), (7,189), (27,286), (92,273)

X(4) = crosssum of X(I) and X(J) for these (I,J):
(4,1075), (6,154), (25,1033), (48,212), (55,198), (56,1035), (71,228), (184,577), (185,417), (216,418)

X(4) = crossdifference of any two points on line X(520)X(647)

X(4) = X(I)-Hirst inverse of X(J) for these (I,J):
(1,243), (2,297), (3,350), (19,242), (21,425), (24,421), (25,419), (27,423), (28,422), (29,415), (420,427), (424,451), (459,460), (470,471), (1249,1503)

X(4) = X(I)-aleph conjugate of X(J) for these (I,J): (1,1047), (29,4)

X(4) = X(I)-beth conjugate of X(J) for these (I,J):
(4,34), (8,40), (29,4), (162,56), (318,318), (811,331)


X(5) = NINE-POINT CENTER

Trilinears       cos(B - C) : cos(C - A) : cos(A - B)
                        = f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = cos A + 2 cos B cos C
                        = g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = cos A - 2 sin B sin C
                        = h(a,b,c) : h(b,c,a) : h(c,a,b), where h(a,b,c) = bc[a2(b2 + c2) - (b2 - c2)2]

Barycentrics  a cos(B - C) : b cos(C - A) : c cos(A - B)
                        = h(a,b,c) : h(b,c,a) : h(c,a,b), where h(a,b,c) = a2(b2 + c2) - (b2 - c2)2

X(5) is the center of the nine-point circle. Euler showed in that this circle passes through the midpoints of the sides of ABC and the feet of the altitudes of ABC, hence six of the nine points. The other three are the midpoints of segments A-to-X(4), B-to-X(4), C-to-X(4). The radius of the nine-point circle is one-half the circumradius.

Dan Pedoe, Circles: A Mathematical View, Mathematical Association of America, 1995.

If you have The Geometer's Sketchpad, you can view these sketches: Nine-point center, Euler Line, Roll Circle, MacBeath Inconic

X(5) lies on the Napoleon cubic (also known as the Feuerbach cubic) and these lines:
1,11   2,3   6,68   8,1389   9,1729   10,517   13,18   14,17   15,2913   16,2912   32,230   33,1062   34,1060   39,114   40,1698   46,1836   49,54   51,52   53,216   55,498   56,499   57,1728   65,1737   69,1351   72,908   76,262   79,1749   83,98   85,1565   96,1166   113,125   116,118   117,124   122,133   127,132   128,137   129,130   131,136   141,211   142,971   156,184   182,206   183,315   195,3459   217,1625   225,1465   226,912   252,1157   264,1093   298,634   299,633   302,622   303,621   311,1225   316,1078   339,1235   371,590   372,615   386,1834   388,999   392,1512   491,637   492,638   515,1125   524,576   539,1493   542,575   570,1879   573,1213   578,1147   579,1901   582,1754   601,750   602,748   618,629   619,630   842,1287   920,1454   1073,1217   1090,1091   1155,1770   1173,1487   1181,1899   1214,1838   1498,1853   1848,1871   1861,1872   2120,2121   3460,3461   3462,3463   3468,3469   3470,3471

X(5) is the {X(2),X(4)}-harmonic conjugate of X(3). For a list of other harmonic conjugates of X(5), click Tables at the top of this page.

X(5) = homothetic center of medial triangle and Euler triangle
X(5) = homothetic center of ABC and the triangle obtained by reflecting X(3) in the points A, B, C
X(5) = radical center of the Stammler circles
X(5) = centroid of {A, B, C, X(4)} (Randy Hutson, August 23, 2011)

X(5) = midpoint of X(I) and X(J) for these (I,J):
(1,355), (2,381), (3,4), (11,119), (20,382), (68,155), (110,265), (113,125), (114,115), (116,118), (117,124), (122,133), (127,132), (128,137), (129,130), (131,136), (399,3448)

X(5) = reflection of X(I) in X(J) for these (I,J): (2,547), (3,140), (4,546), (20,548), (52,143), (549,2), (550,3), (1263,137), (1353,6), (1385,1125), (1483,1), (1484,11)

X(5) = isogonal conjugate of X(54)
X(5) = isotomic conjugate of X(95)
X(5) = inverse-in-circumcircle of X(2070)
X(5) = inverse-in-orthocentroidal-circle of X(3)
X(5) = complement of X(3)
X(5) = anticomplement of X(140)
X(5) = complementary conjugate of X(3)
X(5) = eigencenter of anticevian triangle of X(523)

X(5) = X(I)-Ceva conjugate of X(J) for these (I,J):
(2,216), (4,52), (110,523), (264, 324), (265,30), (311,343), (324,53)

X(5) = cevapoint of X(I) and X(J) for these (I,J): (3,195), (51,216)

X(5) = X(I)-cross conjugate of X(J) for these (I,J): (51,53), (54, 2121), (216,343), (233,2)
X(5) = crosspoint of X(I) and X(J) for these (I,J): (2,264), (311,324)
X(5) = crosssum of X(I) and X(J) for these (I,J): (3,1147), (6,184)
X(5) = crossdifference of any two points on line X(50)X(647)
X(5) = X(1)-aleph conjugate of X(1048)


X(6) = SYMMEDIAN POINT (LEMOINE POINT, GREBE POINT)

Trilinears       a : b : c
                        = sin A : sin B : sin C

Barycentrics  a2 : b2 : c2

X(6) = (r2 + s2 + 2rR)*X(1) - 6rR*X(2) -2r2*X(3)
X(6) = (1 + sqrt(3)*tan(ω))*X(13) + (1 - sqrt(3)*tan(ω))*X(14)
X(6) = (1 + sqrt(3)*tan(ω))*X(15) + (1 - sqrt(3)*tan(ω))*X(16)
X(6) = (3 + 5*sqrt(3)*tan(ω))*X(17) + (3 - 5*sqrt(3)*tan(ω))*X(18)
(The above four combos for X(6) found by Peter Moses, November, 2011)

X(6) is the point of concurrence of the symmedians (i.e., reflections of medians in corresponding angle bisectors). X(6) is the point which, when given by actual trilinear distances x,y,z, minimizes x2 + y2 + z2.

If you have The Geometer's Sketchpad, you can view Symmedian point.

Let A'B'C' be the pedal triangle of an arbitrary point X, and let S(X) be the vector sum XA' + XB' + XC'. Then

S(X) = (0 vector) if and only if X = X(6).


The "if" implication is equivalent to the well known fact that X(6) is the centroid of its pedal triangle, and the converse was proved by Barry Wolk (Hyacinthos #19, Dec. 23, 1999).

X(6) is the radical trace of the 1st and 2nd Lemoine circles. (Peter J. C. Moses, 8/24/03)

X(6) is the perspector of ABC and the medial triangle of the orthic triangle of ABC. (Randy Hutson, 8/23/2011)

Ross Honsberger, Episodes in Nineteenth and Twentieth Century Euclidean Geometry, Mathematical Association of America, 1995. Chapter 7: The Symmedian Point.

X(6) lies on the Thomson cubic and these lines:
1,9   2,69   3,15   4,53   5,68   7,294   8,594   10,1377   13,14   17,18   19,34   21,941   22,251   23,353   24,54   25,51   26,143   27,1246   31,42   33,204   36,609  40,380   41,48   43,87   57,222   60,1169   64,185   66,427   67,125   70,1594   74,112   75,239   76,83   77,241   88,89   98,262   99,729   100,739   101,106   105,1002   110,111   145,346   157,248   160,237   162,1013   169,942   181,197   190,192   194,384   210,612   226,1751   256,1580   264,287   274,1218   279,1170   281,1146   282,1256   291,985   292,869   297,317   305,1241   314,981   330,1258   344,1332   354,374   442,1714   493,1583   494,1584   513,1024   517,998   519,996   523,879   560,1631   561,720   588,1599   589,1600   593,1171   595,1126   598,671   603,1035   644,1120   657,1459   662,757   688,882   689,703   691,843   692,1438   694,1084   706,1502   717,789   750,899   753,825   755,827   840,919   846,1051   893,1403   909,1415   911,1461   939,1802   943,1612   947,1622   959,961   963,1208   967,1790   971,990   986,1046   1073,3343   1096,1859   1112,1177   1131,1132   1139,1140   1166,1601   1173,1614   1174,1617   1195,1399   1201,1696   1214,1708   1327,1328   1362,1416   1398,1425   1423,1429   1718,1781   1826,1837   1836,1839   1854,1858   3342,3351   3344,3350

X(6) is the {X(15),X(16)}-harmonic conjugate of X(3). For a list of other harmonic conjugates of X(6), click Tables at the top of this page.

X(6) = midpoint of X(69) and X(193)
X(6) = reflection of X(I) in X(J) for these (I,J): (1,1386), (2,597), (3,182), (67,125), (69,141), (159,206), (182,575), (592,2), (694,1084), (1350,3), (1351,576), (1352,5)

X(6) = isogonal conjugate of X(2)
X(6) = isotomic conjugate of X(76)
X(6) = cyclocevian conjugate of X(1031)
X(6) = inverse-in-circumcircle of X(187)
X(6) = inverse-in-orthocentroidal-circle of X(115)
X(6) = inverse-in-1st-Lemoine-circle of X(1691)
X(6) = complement of X(69)
X(6) = anticomplement of X(141)
X(6) = anticomplementary conjugate of X(1369)
X(6) = complementary conjugate of X(1368)

X(6) = X(I)-Ceva conjugate of X(J) for these (I,J):
(1,55), (2,3), (3,154), (4,25), (7,1486), (8,197), (9,198), (10,199), (54,184), (57, 56), (58,31), (68,161), (69,159), (74,1495), (76,22), (81,1), (83,2), (88,36), (95,160), (98,237), (110,512), (111,187), (222,221), (249,110), (251,32), (264,157), (275,4), (284,48), (287,1503), (288,54), (323,399), (394,1498)

X(6) = cevapoint of X(I) and X(J) for these (I,J): (1,43), (2,194), (31,41), (32,184), (42,213), (51,217)

X(6) = X(I)-cross conjugate of X(J) for these (I,J):
(25,64), (31,56), (32,25), (39,2), (41,55), (42,1), (51,4), (184,3), (187,111), (213,31), (217,184), (237,98), (512,110)

X(6) = crosspoint of X(I) and X(J) for these (I,J):
(1,57), (2,4), (9,282), (54,275), (58,81), (83, 251), (110,249), (266,289)

X(6) = crosssum of X(I) and X(J) for these (I,J):
(1,9), (3,6), (4,1249), (5,216), (10,37), (11,650), (32,206), (39,141), (44,214), (56,478), (57,223), (114,230), (115,523), (125,647), (128,231), (132,232), (140,233), (142,1212), (188,236), (226,1214), (244,661), (395,619), (396, 618), (512,1084), (513,1015), (514,1086), (522,1146), (570,1209), (577,1147), (590,641), (615,642), (1125,1213), (1196,1368)

X(6) = crossdifference of any two points on line X(30)X(511)

X(6) = X(I)-Hirst inverse of X(J) for these (I,J): (1,238), (2,385), (3,511), (15,16), (25,232), (56,1458), (58,1326), (523,1316), (1423,1429)

X(6) = X(I)-line conjugate of X(J) for these (I,J): (1,518), (2,524), (3,511)
X(6) = X(I)-aleph conjugate of X(J) for these (I,J): (1,846), (81,6), (365,1045), (366,191), (509,1046)

X(6) = X(I)-beth conjugate of X(J) for these (I,J):
(6,604), (9,9), (21,1001), (101,6), (284,6), (294,6), (644,6), (645,6), (651,6), (652,7), (666,6)


X(7) = GERGONNE POINT

Trilinears       bc/(b + c - a) : ca/(c + a - b) : ab/(a + b - c)
                        = sec2(A/2) : sec2(B/2) : sec2(C/2)
                        = 1/(tan(B/2) + tan(C/2)) : 1/(tan(C/2) + tan(A/2)) : 1/(tan(A/2) + tan(B/2))
                        = (bc - SA)/a : (ca - SB)/b : (ab - SC)/c
Barycentrics  1/(b + c - a) : 1/(c + a - b) : 1/(a + b - c)
Barycentrics  tan A/2 : tan B/2 : tan C/2
Barycentrics  bc - SA : ca - SB : ab - SC
X(7) = (2r + 4R)*X(1) + 3r*X(2) - 4r*X(3)

Let A', B', C' denote the points in which the incircle meets the sides BC, CA, AB, respectively. The lines AA', BB', CC' concur in X(7).

If you have The Geometer's Sketchpad, you can view Gergonne point.

X(7) lies on these lines:
1,20   2,9   3,943   4,273   6,294   8,65   11,658   12,1268   21,56   27,81   37,241   33,1041   34,1039   58,272   59,1275   72,443   73,1246   76,1479   80,150   92,189   100,1004   104,934   108,1013   109,675   145,1266   171,983   174,234   177,555   190,344   192,335   193,239   218,277   220,1223   225,969   238,1471   253,280   256,982   274,959   281,653   286,331   310,314   330,1432   349,1269   354,479   404,1259   452,1467   464,1214   480,1376   492,1267   513,885   517,1000   528,664   554,1082   594,599   604,1429   757,1414   840,927   857,1901   870,1431   940,1407   941,1427   944,1389   952,1159   986,1254   987,1106   1002,1362   1020,1765   1061,1870   1354,1367   1365,1366   1386,1456   1419,1449   1435,1848   1486,1602   1617,1621

X(7) is the {X(69),X(75)}-harmonic conjugate of X(8). For a list of other harmonic conjugates of X(7), click Tables at the top of this page.

X(7) = reflection of X(I) in X(J) for these (I,J): (9,142), (144,9), (390,1), (673,1086), (1156,11)
X(7) = isogonal conjugate of X(55)
X(7) = isotomic conjugate of X(8)
X(7) = cyclocevian conjugate of X(7)
X(7) = inverse-in-incircle of (1323)
X(7) = complement of X(144)
X(7) = anticomplement of X(9)
X(7) = complementary conjugate of X(2884)
X(7) = anticomplementary conjugate of X(329)
X(7) = X(I)-Ceva conjugate of X(J) for these (I,J): (75,347), (85,2), (86,77), (286,273), (331,278)

X(7) = cevapoint of X(I) and X(J) for these (I,J):
(1,57), (2,145), (4,196), (11,514), (55,218), (56,222), (63,224), (65,226), (81,229), (177,234)

X(7) = X(I)-cross conjugate of X(J) for these (I,J):
(1,2), (4,189), (11,514), (55,277), (56,278), (57,279), (65,57), (177,174), (222,348), (226,85), (354,1), (497,8), (517,88)

X(7) = crosspoint of X(I) and X(J) for these (I,J): (75,309), (86,286)
X(7) = crosssum of X(I) and X(J) for these (I,J): (41,1253), (42,228)
X(7) = crossdifference of any two points on line X(657)X(663)
X(7) = X(57)-Hirst inverse of X(1447)

X(7) = X(I)-beth conjugate of X(J) for these (I,J):
(7,269), (21,991), (75,75), (86,7), (99,7), (190,7), (290,7), (314,69), (645,344), (648,7), (662,6), (664,7), (666,7), (668,7), (670,7), (671,7), (811,264), (886,7), (889,7), (892,7), (903,7)


X(8) = NAGEL POINT

Trilinears       (b + c - a)/a : (c + a - b)/b : (a + b - c)/c
                        = csc2(A/2) : csc2(B/2) : csc2(C/2)
                        = (bc + SA)/a : (ca + SB)/b : (ab + SC)/c
Barycentrics  b + c - a : c + a - b : a + b - c
Barycentrics  cot A/2 : cot B/2 : cot C/2
Barycentrics  bc + SA : ca + SB : ab + SC
X(8) = 2*X(1) - 3*X(2)

Let A'B'C' be the points in which the A-excircle meets BC, the B-excircle meets CA, and the C-excircle meets AB, respectively. The lines AA', BB', CC' concur in X(8). Another construction of A' is to start at A and trace around ABC half its perimeter, and similarly for B' and C'. Also, X(8) is the incenter of the anticomplementary triangle.

X(8) = perspector of ABC and the intouch triangle of the medial triangle of ABC. (Randy Hutson, 9/23/2011)

If you have The Geometer's Sketchpad, you can view Nagel point.

X(8) lies on these lines:
1,2   3,100   4,72   5,1389   6,594   7,65   9,346   11,1320   19,1891   20,40   21,55   29,219   31,987   33,1039   34,1041   35,993   37,941   38,986   56,404   57,1219   58,996   76,668   79,758   80,149   81,1010   101,1311   140,1483   144,516   171,1468   175,1270   176,1271   177,556   178,236   181,959   190,528   192,256   193,894   194,730   197,1603   210,312   213,981   220,294   221,651   224,914   238,983   253,307   274,1002   277,1280   278,1257   291,330   314,1264   315,760   326,1442   344,480   348,664   392,1000   405,943   406,1061   442,495   443,942   474,999   475,1063   491,1267   595,1724   599,1086   631,1385   643,1098   726,1278   860,1068   908,946   961,1460   1015,1574   1016,1083   1034,1895   1036,1183   1124,1377   1211,1834   1281,1282   1317,1388   1335,1378   1500,1573   1672,1680   1673,1681   1674,1679   1675,1679   1857,1896

X(8) is the {X(69),X(75)}-harmonic conjugate of X(7). For a list of other harmonic conjugates of X(8), click Tables at the top of this page.

X(8) = reflection of X(I) in X(J) for these (I,J): (1,10), (4,355), (20,40), (100,1145), (145,1), (149,80), (192,984), (390,9), (944,2), (962,4), (1320,11), (1482,5), (1483,140)

X(8) = isogonal conjugate of X(56)
X(8) = isotomic conjugate of X(7)
X(8) = cyclocevian conjugate of X(189)
X(8) = complement of X(145)
X(8) = anticomplement of X(1)
X(8) = complementary conjugate of X(2885)
X(8) = anticomplementary conjugate of X(8)
X(8) = X(I)-Ceva conjugate of X(J) for these (I,J): (69,329), (72,2), (312,346), (314,312), (333,9)

X(8) = X(I)-cross conjugate of X(J) for these (I,J):
(1,280), (9,2), (10,318), (11,522), (55,281), (72,78), (200,346), (210,9), (219,345), (497,7), (521,100)

X(8) = cevapoint of X(I) and X(J) for these (I,J):
(1,40), (2,144), (6,197), (9,200), (10,72), (11,522), (55,219), (175,176)

X(8) = crosspoint of X(I) and X(J) for these (I,J): (75,312), (314,333)

X(8) = crosssum of X(I) and X(J) for these (I,J):
(1,978), (31,604), (57,1423), (667,1015), (1042,1410), (1400,1402)

X(8) = crossdifference of any two points on line X(649)X(854)
X(8) = X(1)-aleph conjugate of X(1050)
X(8) = X(I)-beth conjugate of X(J) for these (I,J): (8,1), (341,341), (643,3), (668,8), (1043,8)


X(9) = MITTENPUNKT

Trilinears       b + c - a : c + a - b : a + b - c
                        = cot(A/2) : cot(B/2) : cot(C/2)
Trilinears                               = a - s : b - s : c - s

Barycentrics  a(b + c - a) : b(c + a - b) : c(a + b - c)

X(9) = (r + 2R)*X(1) - 6*X(2) -2r*X(3)

X(9) is the symmedian point of the excentral triangle.

X(9) = perspector of ABC and the medial triangle of the extouch triangle of ABC. (Randy Hutson, 9/23/2011)

If you have The Geometer's Sketchpad, you can view Mittenpunkt.

X(9) lies on the Thomson cubic and these lines:
1,6   2,7   3,84   4,10   5,1729   8,346   21,41   31,612   32,987   33,212   34,201   35,90   38,614   39,978   42,941   43,256   46,79   48,101   55,200   56,1696   58,975   100,1005   164,168   165,910   171,1707   173,177   192,239   223,1073   228,1011   241,269   261,645   294,1253   312,314   318,1896   321,1751   342,653   348,738   364,366   374,517   393,1785   440,1211   478,1038   498,920   522,657   604,1420   607,1039   608,1041   609,1333   644,1320   654,1639   750,896   943,1802   986,1722   991,1818   1088,1223   1125,1732   1174,1621   1249,1712   1377,1703   1378,1702   1479,1752   1571,1574   1572,1573   1678,1705   1679,1704   1680,1701   1681,1700   3341,3344   3343,3352   3349,3351

X(9) is the {X(44),X(45)}-harmonic conjugate of X(1). For a list of other harmonic conjugates of X(9), click Tables at the top of this page. X(9) is the internal center of similitude of the Bevan circle and Spieker circle; the external center is X(1706).

X(9) = midpoint of X(I) and X(J) for these (I,J): (7,144), (8,390)
X(9) = reflection of X(I) in X(J) for these (I,J): (1,1001), (7,142)
X(9) = isogonal conjugate of X(57)
X(9) = isotomic conjugate of X(85)
X(9) = complement of X(7)
X(9) = anticomplement of X(142)
X(9) = X(I)-Ceva conjugate of X(J) for these (I,J):
(2,1), (8,200), (21,55), (63,40), (190,522), (312,78), (318,33), (329, 1490), (333,8)

X(9) = cevapoint of X(I) and X(J) for these (I,J): (1,165), (6,198), (31,205), (37,71), (41,212), (55,220)

X(9) = X(I)-cross conjugate of X(J) for these (I,J):
(6,282), (37,281), (41,33), (55,1), (71,219), (210,8), (212,78), (220,200)

X(9) = crosspoint of X(I) and X(J) for these (I,J): (2,8), (21,333), (63,271), (312,318)
X(9) = crosssum of X(I) and X(J) for these (I,J): (6,56), (19,208), (65,1400), (244,649), (603,604), (1418,1475)
X(9) = crossdifference of any two points on line X(513)X(663)
X(9) = X(I)-Hirst inverse of X(J) for these (I,J): (1, 518), (192,239)

X(9) = X(I)-aleph conjugate of X(J) for these (I,J):
(1,43), (2,9), (9,170), (188,165), (190,1018), (366,1), (507,361), (508,57), (509,978)

X(9) = X(I)-beth conjugate of X(J) for these (I,J):
(9,6), (190,6), (346,346), (644,9), (645,75)


X(10) = SPIEKER CENTER

Trilinears       bc(b + c) : ca(c + a) : ab(a + b)
Barycentrics  b + c : c + a : a + b
X(10) = X(1) - 3*X(2)

The Spieker circle is the incircle of the medial triangle; its center, X(10), is the centroid of the perimeter of ABC.

If you have The Geometer's Sketchpad, you can view Spieker center.

X(10) lies on these lines:
1,2   3,197   4,9   5,517   6,1377   11,121   12,65   20,165   21,35   28,1891   29,1794   31,964   33,406   34,475   36,404   37,594   38,596   39,730   44,752   46,63   55,405   56,474   57,388   58,171   69,969   75,76   81,1224   82,83   86,319   87,979   92,1838   98,101   106,1222   116,120   117,123   119,124   140,214   141,142   150,1282   153,1768   158,318   182,1678   190,671   191,267   201,225   219,965   227,1214   235,1902   255,1771   257,1581   261,1326   274,291   307,1254   321,756   348,1323   391,1743   407,1867   427,1829   429,1824   480,954   485,1686   486,1685   497,1697   514,764   535,1155   537,1086   626,760   631,944   632,1483   750,1150   774,1736   775,801   846,1247   894,1046   908,994   962,1695   1018,1334   1074,1735   1146,1212   1482,1656   1587,1703   1588,1702   1762,1782   1828,1883   1900,1904

X(10) is the {X(1),X(2)}-harmonic conjugate of X(1125). For a list of other harmonic conjugates of X(10), click Tables at the top of this page. X(10) is the internal center of similitude of the Apollonius and nine-points circles.

X(10) is the radical center of the excircles.

X(10) = midpoint of X(I) and X(J) for these (I,J): (1,8), (3,355), (4,40), (6,3416), (10,3421), (55,3419), (65,72), (80,100), (2948,3448)
X(10) = reflection of X(I) in X(J) for these (I,J): (1,1125), (551,2), (946,5), (1385,140)
X(10) = isogonal conjugate of X(58)
X(10) = isotomic conjugate of X(86)
X(10) = inverse-in-circumcircle of X(1324)
X(10) = inverse-in-nine-point-circle of X(3814)
X(10) = complement of X(1)
X(10) = anticomplement of X(1125)
X(10) = complementary conjugate of X(10)
X(10) = anticomplementary conjugate of X(2891)

X(10) = X(I)-Ceva conjugate of X(J) for these (I,J):
(2,37), (8,72), (75,321), (80,519), (100,522), (313,306)

X(10) = cevapoint of X(I) and X(J) for these (I,J): (1,191), (6,199), (12,201), (37,210), (42,71), (65,227)
X(10) = X(I)-cross conjugate of X(J) for these (I,J): (37,226), (71,306), (191,502), (201,72)
X(10) = crosspoint of X(I) and X(J) for these (I,J): (2,75), (8,318)
X(10) = crosssum of X(I) and X(J) for these (I,J): (6,31), (56,603)
X(10) = crossdifference of any two points on line X(649)X(834)
X(10) = X(I)-beth conjugate of X(J) for these (I,J): (8,10), (10,65), (100,73), (318,225), (643,35), (668,349)


X(11) = FEUERBACH POINT

Trilinears       1 - cos(B - C) : 1 - cos(C - A) : 1 - cos(A - B)
                        = f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin2(B/2 - C/2)
                        = g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = bc(b + c - a)(b - c)2

Barycentrics  a(1 - cos(B - C)) : b(1 - cos(C - A)) : c(1 - cos(A - B))
                         = h(a,b,c) : h(b,c,a) : h(c,a,b), where h(A,B,C) = (b + c - a)(b - c)2

X(11) = R*X(1) - 3rX(2) + r*X(3)

X(11) is the point of tangency of the nine-point circle and the incircle. The nine-point circle is the circumcenter of the medial triangle, as well as the orthic triangle. Feuerbach's famous theorem states that the nine-point circle is tangent to the incircle and the three excircles.

If you have The Geometer's Sketchpad, you can view Feuerbach point.

X(11) is the {X(1),X(5)}-harmonic conjugate of X(12) and also the {X(5),X(12)}-harmonic conjugate of X(3614) . For a list of other harmonic conjugates of X(11), click Tables at the top of this page.

X(11) lies on these lines:
1,5   2,55   3,499   4,56   7,658   8,1320   10,121   13,202   14,203   28,1852   30,36   33,427   34,235   35,140   57,1360   65,117   68,1069   110,215   113,942   115,1015   118,226   124,1364   182,1848   133,1838   153,388   212,748   214,442   244,867   278,1857   325,350   381,999   403,1870   429,1104   485,1124   486,1335   498,1656   515,1319   516,1155   517,1737   518,908   523,1090   613,1352   650,1566   774,1393   944,1388   962,1788   971,1538   1012,1470   1040,1368   1111,1358   1146,1639   1193,1834   1427,1856   1428,1503   1455,1877   1500,1506   1697,1698

X(11) = midpoint of X(I) and X(J) for these (I,J): (1,80), (4,104), (5,1484), (9,3254), (100,149)
X(11) = reflection of X(I) in X(J) for these (I,J): (1,1387), (119,5), (214,1125), (1145,10), (1317,1), (1537,946)
X(11) = isogonal conjugate of X(59)
X(11) = isotomic conjugate of X(4998)
X(11) = inverse-in-Fuhrmann-circle of X(1837)
X(11) = complement of X(100)
X(11) = anticomplement of X(3035)
X(11) = complementary conjugate of X(513)
X(11) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,523), (4,513), (7,514), (8,522), (262,1491)
X(11) = crosspoint of X(I) and X(J) for these (I,J): (7,514), (8,522)
X(11) = crosssum of X(I) and X(J) for these (I,J): (6,692), (55,101), (56,109), (1381,1382), (1397,1415)
X(11) = crossdifference of any two points on line X(101)X(109)
X(11) = X(I)-beth conjugate of X(J) for these (I,J): (11,244), (522,11), (693,11)


X(12) = {X(1),X(5)}-HARMONIC CONJUGATE OF X(11)

Trilinears       1 + cos(B - C) : 1 + cos(C - A) : 1 + cos(A - B)
                        = f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = cos2(B/2 - C/2)
                        = g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = bc(b + c)2/(b + c - a)

Barycentrics  a(1 + cos(B - C)) : b(1 + cos(C - A)) : c(1 + cos(A - B))
                         = h(a,b,c) : h(b,c,a) : h(c,a,b), where h(a,b,c) = (b + c)2/(b + c - a)

X(12) = R*X(1) + 3r*X(2) - r*X(3)

Let A'B'C' be the touch points of the nine-point circle with the A-, B-, C- excircles, respectively. The lines AA', BB', CC' concur in X(12).

X(12) lies on these lines:
1,5   2,56   3,498   4,55   7,1268   10,65   17,203   18,202   30,35   33,235   34,427   36,140   37,225   38,1393   40,1836   42,1834   54,215   57,1224   63,1454   71,1901   79,484   85,120   108,451   115,1500   116,1362   117,1364   121,1357   123,1359   124,1361   125,1425   141,1469   171,1399   172,230   201,756   208,1360   221,1853   228,407   281,1118   313,349   354,1210   377,1259   381,1479   431,1824   443,1466   474,1470   485,1124   486,1124   499,999   603,750   611,1352   908,960   942,1209   946,1532   968,1904   1015,1506   1038,1368   1091,1109   1125,1319   1213,1400   1452,1892   1594,1870   1697,1699   1861,1887   1877,1883

X(12) is the {X(1),X(5)}-harmonic conjugate of X(11). For a list of other harmonic conjugates of X(12), click Tables at the top of this page.

If you have The Geometer's Sketchpad, you can view X(12).

X(12) = isogonal conjugate of X(60)
X(12) = isotomic conjugate of X(261)
X(12) = complement of X(2975)
X(12) = X(10)-Ceva conjugate of X(201)
X(12) = crosssum of X(58) and X(1437)
X(12) = X(I)-beth conjugate of X(J) for these (I,J): (10,12), (1089,1089)


X(13) = 1st ISOGONIC CENTER (FERMAT POINT, TORRICELLI POINT)

Trilinears       csc(A + π/3) : csc(B + π/3) : csc(C + π/3)
                        = sec(A - π/6) : sec(B - π/6) : sec(C - π/6)

Barycentrics  f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = a4 - 2(b2 - c2)2 + a2(b2 + c2 + 4*sqrt(3)*Area(ABC))

X(13) = 31/2(r2 + 2rR + s2)*X(1) - 6r(31/2R - 2s)*X(2) - 2r(31/2r + 3s)*X(3)
   (Peter Moses, April 2, 2013)

Construct the equilateral triangle BA'C having base BC and vertex A' on the negative side of BC; similarly construct equilateral triangles CB'A and AC'B based on the other two sides. The lines AA',BB',CC' concur in X(13). If each of the angles A, B, C is < 2π/3, then X(13) is the only center X for which the angles BXC, CXA, AXB are equal, and X(13) minimizes the sum |AX| + |BX| + |CX|. The antipedal triangle of X(13) is equilateral.

If, however, A> 2π/3, then the Fermat point, defined geometrically as the minimizer of |AX| + |BX| + |CX|, is not the 1st isogonic center (which is defined by the above trilinears). Trilinears for the Fermat point when A> 2π/3 are simply 1:0:0. To represent the Fermat point in the form f(a,b,c) : f(b,c,a) : f(c,a,b), one must use Boolean variables, as shown at Fermat point.

If you have The Geometer's Sketchpad, you can view these sketches:
Fermat Dynamic
1st isogonic center
Kiepert Hyperbola, showing X(13) and X(14) on the hyperbola, with midpoint X(115).
Evans Conic, passing through X(13), X(14), X(15), X(16), X(17), X(18), X(3070), X(3071).
X(3054), center of the Evans Conic and 19 other triangle centers.

The Evans conic is introduced in

Evans, Lawrence S., "A Conic Through Six Triangle Centers," Forum Geometricorum 2 (2002) 89-92.

X(13) lies on the Neuberg cubic and these lines:
2,16   3,17   4,61   5,18   6,14   11,202   15,30   76,299   80,1251   98,1080   99,303   148,617   203,1478   226,1081   262,383   275,472   298,532   484,1277   531,671   533,621   634,635

X(13) is the {X(6),X(381)}-harmonic conjugate of X(14). For a list of other harmonic conjugates of X(13), click Tables at the top of this page.

X(13) = reflection of X(I) in X(J) for these (I,J): (14,115), (15,396), (99,619), (298,623), (616,618)
X(13) = isogonal conjugate of X(15)
X(13) = isotomic conjugate of X(298)
X(13) = inverse-in-orthocentroidal-circle of X(14)
X(13) = complement of X(616)
X(13) = anticomplement of X(618)
X(13) = cevapoint of X(15) and X(62)
X(13) = X(I)-cross conjugate of X(J) for these (I,J): (15,18), (30,14), (396,2)


X(14) = 2nd ISOGONIC CENTER

Trilinears       csc(A - π/3) : csc(B - π/3) : csc(C - π/3)
                        = sec(A + π/6) : sec(B + π/6) : sec(C + π/6)

Barycentrics  f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = a4 - 2(b2 - c2)2 + a2(b2 + c2 - 4*sqrt(3)*Area(ABC))

X(14) = 31/2(r2 + 2rR + s2)*X(1) - 6r(31/2R + 2s)*X(2) + 2r(31/2r - 3s)*X(3)
   (Peter Moses, April 2, 2013)

Construct the equilateral triangle BA'C having base BC and vertex A' on the positive side of BC; similarly construct equilateral triangles CB'A and AC'B based on the other two sides. The lines AA',BB',CC' concur in X(14). The antipedal triangle of X(14) is equilateral.

If you have The Geometer's Sketchpad, you can view 2nd isogonic center

X(14) lies on the Neuberg cubic and these lines:
2,15   3,18   4,62   5,17   6,13   11,203   16,30   76,298   98,383   99,302   148,616   202,1478   226,554   262,1080   275,473   299,533   397,546   484,1276   530,671   532,622   633,636

X(14) is the {X(6),X(381)}-harmonic conjugate of X(13). For a list of other harmonic conjugates of X(14), click Tables at the top of this page.

X(14) = reflection of X(I) in X(J) for these (I,J): (13,115), (16,395), (99,618), (299,624), (617,619)
X(14) = isogonal conjugate of X(16)
X(14) = isotomic conjugate of X(299)
X(14) = inverse-in-orthocentroidal-circle of X(13)
X(14) = complement of X(617)
X(14) = anticomplement of X(619)
X(14) = cevapoint of X(16) and X(61)
X(14) = X(I)-cross conjugate of X(J) for these (I,J): (16,17), (30,13), (395,2)


X(15) = 1st ISODYNAMIC POINT

Trilinears       sin(A + π/3) : sin(B + π/3) : sin(C + π/3)
                        = cos(A - π/6) : cos(B - π/6) : cos(C - π/6)
Barycentrics  a sin(A + π/3) : b sin(B + π/3) : c sin(C + π/3)
X(15) = (r2 + 2rR + s2)*X(1) - 6rR*X(2) - 2r(r - 31/2s)*X(3)
   (Peter Moses, April 2, 2013)
X(15) = sqrt(3)*X(3) + (cot ω)*X(6)

Let U and V be the points on sideline BC met by the interior and exterior bisectors of angle A. The circle having diameter UV is the A-Apollonian circle. The B- and C- Apollonian circles are similarly constructed. Each circle passes through one vertex and both isodynamic points. (This configuration, based on the cevians of X(1), generalizes to arbitrary cevians; see TCCT, p. 98, problem 8.)

The pedal triangle of X(15) is equilateral.

If you have The Geometer's Sketchpad, you can view 1st isodynamic point and X(15)&X(16), with Brocard axis and Lemoine axis.

X(15) lies on the Neuberg cubic and these lines:
1,1251   2,14   3,6   4,17   13,30   18,140   35,1250   36,202   55,203   298,533   303,316   395,549   397,550   532,616   628,636

X(15) is the {X(3),X(6)}-harmonic conjugate of X(16). For a list of other harmonic conjugates of X(15), click Tables at the top of this page.

X(15) = reflection of X(I) in X(J) for these (I,J): (13,396), (16,187), (298,618), (316,624), (621,623)
X(15) = isogonal conjugate of X(13)
X(15) = isotomic conjugate of X(300)
X(15) = inverse-in-circumcircle of X(16)
X(15) = inverse-in-Brocard-circle of X(16)
X(15) = complement of X(621)
X(15) = anticomplement of X(623)
X(15) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,202), (13,62), (74,16)
X(15) = crosspoint of X(I) and X(J) for these (I,J): (13,18), (298,470)
X(15) = crosssum of X(I) and X(J) for these (I,J): (15,62), (532,619)
X(15) = crossdifference of any two points on line X(395)X(523)
X(15) = X(6)-Hirst inverse of X(16)


X(16) = 2nd ISODYNAMIC POINT

Trilinears       sin(A - π/3) : sin(B - π/3) : sin(C - π/3)
                        = cos(A + π/6) : cos(B + π/6) : cos(C + π/6)
Barycentrics  a sin(A - π/3) : b sin(B - π/3) : c sin(C - π/3)
X(16) = -(r2 + 2rR + s2)*X(1) + 6rR*X(2) + 2r(r + 31/2s)*X(3)
   (Peter Moses, April 2, 2013)
X(16) = sqrt(3)*X(3) - (cot ω)*X(6)

Let U and V be the points on sideline BC met by the interior and exterior bisectors of angle A. The circle having diameter UV is the A-Apollonian circle. The B- and C- Apollonian circles are similarly constructed. Each circle passes through a vertex and both isodynamic points. The pedal triangle of X(16) is equilateral.

If you have The Geometer's Sketchpad, you can view 2nd isodynamic point.

X(16) lies on the Neuberg cubic and these lines:
1,1250   2,13   3,6   4,18   14,30   17,140   36,203   55,202   299,532   302,316   358,1135   396,549   398,550   533,617   627,635

X(16) is the {X(3),X(6)}-harmonic conjugate of X(15). For a list of other harmonic conjugates of X(16), click Tables at the top of this page.

X(16) = reflection of X(I) in X(J) for these (I,J): (14,395), (15,187), (299,619), (316,623), (622,624)
X(16) = isogonal conjugate of X(14)
X(16) = isotomic conjugate of X(301)
X(16) = inverse-in-circumcircle of X(15)
X(16) = inverse-in-Brocard-circle of X(15)
X(16) = complement of X(622)
X(16) = anticomplement of X(624)
X(16) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,203), (14,61), (74,15)
X(16) = crosspoint of X(I) and X(J) for these (I,J): (14,17), (299,471)
X(16) = crosssum of X(I) and X(J) for these (I,J): (16,61), (533,618)
X(16) = crossdifference of any two points on line X(396)X(523)
X(16) = X(6)-Hirst inverse of X(15)


X(17) = 1st NAPOLEON POINT

Trilinears       csc(A + π/6) : csc(B + π/6) : csc(C + π/6)
                        = sec(A - π/3) : sec(B - π/3) : sec(C - π/3)

Barycentrics  a csc(A + π/6) : b csc(B + π/6) : c csc(C + π/6)

Let X,Y,Z be the centers of the equilateral triangles in the construction of X(13). The lines AX, BY, CZ concur in X(17).

John Rigby, "Napoleon revisited," Journal of Geometry, 33 (1988) 126-146.

If you have The Geometer's Sketchpad, you can view 1st Napoleon point.

X(17) lies on the Napoleon cubic and these lines:
2,62   3,13   4,15   5,14   6,18   12,203   16,140   76,303   83,624   202,499   275,471   299,635   623,633

X(17) is the {X(231),X(1209)}-harmonic conjugate of X(18). For a list of other harmonic conjugates of X(17), click Tables at the top of this page.

X(17) = reflection of X(627) in X(629)
X(17) = isogonal conjugate of X(61)
X(17) = isotomic conjugate of X(302)
X(17) = complement of X(627)
X(17) = anticomplement of X(629)
X(17) = X(I)-cross conjugate of X(J) for these (I,J): (16,14), (140,18), (397,4)


X(18) = 2nd NAPOLEON POINT

Trilinears       csc(A - π/6) : csc(B - π/6) : csc(C - π/6)
                        = sec(A + π/3) : sec(B + π/3) : sec(C + π/3)

Barycentrics  a csc(A - π/6) : b csc(B - π/6) : c csc(C - π/6)

Let X,Y,Z be the centers of the equilateral triangles in the construction of X(14). The lines AX, BY, CZ concur in X(18).

If you have The Geometer's Sketchpad, you can view 2nd Napoleon point.

X(18) lies on the Napoleon cubic and these lines:
2,61   3,14   4,16   5,13   6,17   12,202   15,140   76,302   83,623   203,499   275,470   298,636   624,634

X(18) is the {X(231),X(1209)}-harmonic conjugate of X(17). For a list of other harmonic conjugates of X(18), click Tables at the top of this page.

X(18) = reflection of X(628) in X(630)
X(18) = isogonal conjugate of X(62)
X(18) = isotomic conjugate of X(303)
X(18) = complement of X(628)
X(18) = anticomplement of X(630)
X(18) = X(I)-cross conjugate of X(J) for these (I,J): (15,13), (140,17), (398,4)


X(19) = CLAWSON POINT

Trilinears       tan A : tan B : tan C
                        = f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin 2B + sin 2C - sin 2A
                        = g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = 1/(b2 + c2 - a2)
                        = g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = a2 - S2 + SA

Barycentrics  a tan A : b tan B : c tan C

X(19) = (r + 2R - s)(r + 2R + s)*X(1) - 6R(r + 2R)*X(2) - 2(r2 + 2rR - s2)*X(3)   (Peter Moses, April 2, 2013)

X(19) is the homothetic center of the orthic and extangents triangles. The Ayme triangle, constructed at X(3610), is perspective to ABC with perspector X(19).

If you have The Geometer's Sketchpad, you can view Clawson point.

Further information is available from
Paul Yiu's Website.

Although John Clawson studied this point in 1925, it was studied earlier by Lemoine:

Emile Lemoine, "Quelques questions se rapportant à l'étude des antiparallèles des côtes d'un triangle", Bulletin de la S. M. F., tome 14 (1886), p. 107-128, specifically, on page 114. This article is available online at Numdam.

X(19) lies on these lines:
1,28   2,534   3,1871   4,9   6,34   8,1891   25,33   27,63   31,204   41,1825   44,1828   45,1900   46,579   47,921   53,1846   56,207   57,196   64,1903   81,969   91,920   101,913   102,282   112,759   158,1712   162,897   163,563   208,225   219,517   220,1902   226,1763   232,444   273,653   294,1041   318,1840   379,1441   407,1865   429,1213   560,1910   604,909   672,1851   960,965   1158,1715   1212,1593   1405,1866   1449,1870   1581,1740   1598,1872   1633,1721   1707,1719   1708,1713   1743,1783   1836,1901   1837,1852

X(19) is the {X(607),X(608)}-harmonic conjugate of X(6). For a list of other harmonic conjugates of X(19), click Tables at the top of this page.

X(19) = isogonal conjugate of X(63)
X(19) = isotomic conjugate of X(304)

X(19) = X(I)-Ceva conjugate of X(J) for these (I,J):
(1,204), (4,33), (27,4), (28,25), (57,208), (92,1), (196,207), (278,34)

X(19) = X(I)-cross conjugate of X(J) for these (I,J): (25,34), (31,1)
X(19) = crosspoint of X(I) and X(J) for these (I,J): (4,278), (27,28), (57,84), (92,158)
X(19) = crosssum of X(I) and X(J) for these (I,J): (1,610), (3,219), (9,40), (48,255), (71,72)
X(19) = crossdifference of any two points on line X(521)X(656)
X(19) = X(I)-Hirst inverse of X(J) for these (I,J): (1,240), (4,242)
X(19) = X(I)-aleph conjugate of X(J) for these (I,J): (2,610), (92,19), (508,223), (648,163)
X(19) = X(I)-beth conjugate of X(J) for these (I,J): (9,198), (19,608), (112,604), (281,281), (648,273), (653,19)



leftri Centers 20- 30, rightri
2- 5, 140, 186, 199, 235, 237, 297, 376- 379, 381- 384,
401- 475, 546- 550, 631, 632 (and others) lie on the Euler line.

underbar

X(20) = DE LONGCHAMPS POINT

Trilinears       cos A - cos B cos C : cos B - cos C cos A : cos C - cos A cos B
                        = sec A - sec B sec C : sec B - sec C sec A : sec C - sec A sec B
                        = 2 cos A - sin B sin C : 2 cos B - sin C sin A : 2 cos C - sin A sin B

Barycentrics  tan B + tan C - tan A : tan C + tan A - tan B : tan A + tan B - tan C
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [-3a4 + 2a2(b2 + c2) + (b2 - c2)2]
X(20) = 2(r + 2R)*X(1) - (r +4R)*X(7) = 3X(2) - 4X(3) = X(8) - 2X(40)

X(20) is the reflection of X(4) in X(3); also, the orthocenter of the anticomplementary triangle.

If you have The Geometer's Sketchpad, you can view De Longchamps point.

X(20) lies on the Darboux cubic and these lines:
1,7   2,3   8,40   10,165   33,1038   34,1040   35,1478   36,1479   55,388   56,497   57,938   58,387   64,69   68,74   72,144   78,329   97,1217   98,148   99,147   100,153   101,152   103,150   104,149   109,151   110,146   145,517   155,323   185,193   190,1265   243,1118   254,1300   346,1766   371,1587   372,1588   391,573   393,577   394,1032   485,1131   486,1132   487,638   488,637   616,633   617,635   621,627   622,628   936,1750   999,1058   1062,1870   1074,1838   1076,1785   1125,1699   1147,1614   1155,1788   1204,1899   1440,1804   1610,1633   2130,2131   3182,3347   3183,3348   3353,3354   3472,3473

X(20) is the {X(3),X(4)}-harmonic conjugate of X(2). For a list of other harmonic conjugates of X(20), click Tables at the top of this page.

X(20) = reflection of X(I) in X(J) for these (I,J): (2,376), (3,550), (4,3), (5,548), (8,40), (69,1350), (145,944), (146,110), (147,99), (148,98), (149,104), (150,103), (151,109), (152,101), (153,100), (382,5), (962,1)

X(20) = isogonal conjugate of X(64)
X(20) = isotomic conjugate of X(253)
X(20) = cyclocevian conjugate of X(1032)
X(20) = inverse-in-circumcircle of X(2071)
X(20) = inverse-in-orthocentroidal-circle of X(3091)
X(20) = complement of X(3146)
X(20) = anticomplement of X(4)
X(20) = anticomplementary conjugate of X(4)
X(20) = X(I)-Ceva conjugate of X(J) for these (I,J): (69,2), (489,487), (490,488)
X(20) = crosssum of X(1) and X(1044)
X(20) = crossdifference of any two points on line X(647)X(657)
X(20) = X(I)-aleph conjugate of X(J) for these (I,J): (8,191), (9,1045), (188,1046), (333,2), (1043,20)
X(20) = X(I)-beth conjugate of X(J) for these (I,J): (664,20), (1043,280)


X(21) = SCHIFFLER POINT

Trilinears       1/(cos B + cos C) : 1/(cos C + cos A) : 1/(cos A + cos B)
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (b + c - a)/(b + c)
Barycentrics  a/(cos B + cos C) : b/(cos C + cos A) : c/(cos A + cos B)

X(21) = 3R*X(2) + 2r*X(3)

Let A'B'C' be the incentral triangle of ABC, and let LA be the reflection of line B'C' in line BC; define LB and LC cyclically. The triangle formed by the lines LA, LB, LC is perspective to ABC, and the perspector is X(21). (Randy Hutson, 9/23/2011)

Write I for the incenter; the Euler lines of the four triangles IBC, ICA, IAB, and ABC concur in X(21). This configuration extends to Kirikami-Schiffler points and generalizations found by Peter Moses, as introduced just before X(3648).

If you have The Geometer's Sketchpad, you can view Schiffler point.

Lev Emelyanov and Tatiana Emelyanova, A note on the Schiffler point, Forum Geometricorum 3 (2003) pages 113-116.

The name of this point honors Kurt Schiffler.

X(21) lies on these lines:
1,31   2,3   6,941   7,56   8,55   9,41   10,35   32,981   36,79   37,172   51,970   60,960   72,943   75,272   77,1394   84,285   90,224   99,105   104,110   107,1295   144,954   145,956   238,256   243,1896   261,314   268,280   270,1172   286,1441   294,1212   332,1036   385,1655   386,1724   517,1389   572,1765   612,989   614,988   643,1320   644,1334   662,1156   741,932   748,978   884,885   915,925   961,1402   976,983   1030,1213   1038,1041   1039,1040   1060,1063   1061,1062   1214,1396   1254,1758   1319,1408   1412,1420

X(21) is the {X(2),X(3)}-harmonic conjugate of X(404). For a list of other harmonic conjugates of X(21), click Tables at the top of this page.

X(21) = midpoint of X(1) and X(191)
X(21) = isogonal conjugate of X(65)
X(21) = isotomic conjugate of X(1441)
X(21) = inverse-in-circumcircle of X(1325)
X(21) = anticomplement of X(442)
X(21) = X(I)-Ceva conjugate of X(J) for these (I,J): (86,81), (261,333)
X(21) = cevapoint of X(I) and X(J) for these (I,J): (1,3), (9,55)

X(21) = X(I)-cross conjugate of X(J) for these (I,J):
(1,29), (3,283), (9,333), (55,284), (58,285), (284,81), (522,100)

X(21) = crosspoint of X(86) and X(333)
X(21) = crosssum of X(I) and X(J) for these (I,J): (1,1046), (42,1400), (1254,1425), (1402,1409)
X(21) = crossdifference of any two points on line X(647)X(661)
X(21) = X(I)-Hirst inverse of X(J) for these (I,J): (2,448), (3,416), (4,425)
X(21) = X(I)-beth conjugate of X(J) for these (I,J): (21,58), (99,21), (643,21), (1043,1043), (1098,21)


X(22) = EXETER POINT

Trilinears       a(b4 + c4 - a4) : b(c4 + a4 - b4) : c(a4 + b4 - c4)
Barycentrics  a2(b4 + c4 - a4) : b2(c4 + a4 - b4) : c2(a4 + b4 - c4)
Barycentrics  sin 2A - tan ω : sin 2B - tan ω : sin 2C - tan ω     (M. Iliev, 5/13/07)

X(22) is the perspector of the circummedial triangle and the tangential triangle; also X(22) = X(55)-of-the-tangential triangle if ABC is acute. See the note just before X(1601) for a generalization.

If you have The Geometer's Sketchpad, you can view Exeter point.

X(22) lies on these lines:
2,3   6,251   32,1194   35,612   36,614   51,182   56,977   69,159   76,1799   98,925   99,305   100,197   110,154   155,1614   157,183   160,325   161,343   184,511   187,1196   232,577   264,1629   347,1617   675,1305   991,1790   1184,1627   1294,1302   1486,1621   1602,1626

X(22) is the {X(3),X(25)}-harmonic conjugate of X(2). For a list of other harmonic conjugates of X(22), click Tables at the top of this page.

X(22) = reflection of X(378) in X(3)
X(22) = isogonal conjugate of X(66)
X(22) = inverse-in-circumcircle of X(858)
X(22) = anticomplement of X(427)
X(22) = X(76)-Ceva conjugate of X(6)
X(22) = cevapoint of X(3) and X(159)
X(22) = crosspoint of X(99) and X(250)
X(22) = crosssum of X(125) and X(512)
X(22) = crossdifference of any two points on line X(647)X(826)
X(22) = X(I)-beth conjugate of X(J) for these (I,J): (643,345), (833,22)


X(23) = FAR-OUT POINT

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a[b4 + c4 - a4 - b2c2]
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)
Barycentrics  2 sin 2A - 3 tan ω : 2 sin 2B - 3 tan ω : 2 sin 2C - 3 tan ω     (M. Iliev, 5/13/07)

X(23) is the inverse-in-circumcircle of X(2).

If you have The Geometer's Sketchpad, you can view Far-out point.

X(23) lies on these lines:
2,3   6,353   51,575   52,1614   94,98   105,1290   110,323   111,187   143,1199   159,193   184,576   232,250   251,1194   324,1629   385,523   477,1302   895,1177   1196,1627   1297,1804

X(23) is the {X(22),X(25)}-harmonic conjugate of X(2). For a list of other harmonic conjugates of X(23), click Tables at the top of this page.

X(23) = reflection of X(I) in X(J) for these (I,J): (110,1495), (323,110), (691,187), (858,468)
X(23) = isogonal conjugate of X(67)
X(23) = inverse-in-circumcircle of X(2)
X(23) = anticomplement of X(858)
X(23) = anticomplementary conjugate of X(2892)
X(23) = crosspoint of X(111) and X(251)
X(23) = crosssum of X(I) and X(J) for these (I,J): (125,690), (141,524)
X(23) = crossdifference of any two points on line X(39)X(647)


X(24) = PERSPECTOR OF ABC AND ORTHIC-OF-ORTHIC TRIANGLE

Trilinears       sec A cos 2A : sec B cos 2B : sec C cos 2C
                        = sec A - 2 cos A : sec B - 2 cos B : sec C - 2 cos C

Barycentrics   tan A cos 2A : tan B cos 2B : tan C cos 2C
                        = tan A - sin 2A : tan A - sin 2B : tan C - sin 2C

Constructed as indicated by the name; also X(24) = X(56)-of-the-tangential triangle if ABC is acute.

X(24) = homothetic center of the tangential triangle and the triangle obtained by reflecting X(4) in the points A, B, C.

If you have The Geometer's Sketchpad, you can view X(24).

X(24) lies on these lines:
1,1061   2,3   6,54   32,232   33,35   34,36   49,568   51,578   52,1147   56,1870   64,74   96,847   98,1289   107,1093   108,915   110,155   154,1181   182,1843   183,1235   184,389   185,1495   242,1602   254,393   264,1078   511,1092   573,1474   602,1395   944,1610   1063,1775   1112,1511   1192,1511   1324,1603   1385,1829

X(24) is the {X(3),X(4)}-harmonic conjugate of X(378). For a list of other harmonic conjugates of X(24), click Tables at the top of this page.

X(24) = reflection of X(4) in X(235)
X(24) = isogonal conjugate of X(68)
X(24) = inverse-in-circumcircle of X(403)
X(24) = inverse-in-orthocentroidal circle of X(1594)
X(24) = X(249)-Ceva conjugate of X(112)
X(24) = X(52)-cross conjugate of X(4)
X(24) = crosspoint of X(107) and X(250)
X(24) = crosssum of X(I) and X(J) for these (I,J): (6,161), (125,520), (637,638)
X(24) = X(4)-Hirst inverse of X(421)


X(25) = HOMOTHETIC CENTER OF ORTHIC AND TANGENTIAL TRIANGLES

Trilinears       sin A tan A : sin B tan B : sin C tan C = cos A - sec A : cos B - sec B : cos C - sec C
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a/(b2 + c2 - a2)

Barycentrics  sin 2A - 2 tan A : sin 2B - 2 tan B : sin 2C - 2 tan C
                        = g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = a2/(b2 + c2 - a2)

Constructed as indicated by the name; also X(25) is the pole of the orthic axis (the line having trilinear coefficients cos A : cos B : cos C) with respect to the circumcircle. Also, X(25) is X(57)-of-the-tangential triangle.

X(25) = perspector of ABC and the pedal triangle of X(4) in the orthic triangle

If you have The Geometer's Sketchpad, you can view X(25).

X(25) lies on these lines:
1,1036   2,3   6,51   19,33   31,608   32,1184   34,56   35,1900   36,1878   40,1902   41,42   52,155   53,157   57,1473   58,967   64,1192   65,1452   76,1241   92,242   98,107   100,1862   105,108   110,1112   111,112   114,135   125,1853   132,136   143,156   183,264   185,1498   221,1425   225,1842   226,1892   262,275   273,1447   286,1218   317,325   339,1289   343,1352   371,493   372,494   389,1181   393,1033   394,511   669,878   692,913   694,1613   842,1304   847,1179   941,1172   958,1891   999,1870   1001,1848   1073,1297   1096,1402   1235,1239   1300,1302   1324,1785   1376,1861   1470,1877   1503,1619   1604,1863   1631,1826   1726,1736   1730,1754

X(25) is the {X(5),X(26)}-harmonic conjugate of X(3). For a list of other harmonic conjugates of X(25), click Tables at the top of this page.

X(25) = reflection of X(I) in X(J) for these (I,J): (4,1596), (1370,1368)
X(25) = isogonal conjugate of X(69)
X(25) = isotomic conjugate of X(305)
X(25) = inverse-in-circumcircle of X(468)
X(25) = inverse-in-orthocentroidal-circle of X(427)
X(25) = complement of X(1370)
X(25) = anticomplement of X(1368)
X(25) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,6), (28,19), (250,112)
X(25) = X(32)-cross conjugate of X(6)
X(25) = crosspoint of X(I) and X(J) for these (I,J): (4,393), (6,64), (19,34), (112,250)
X(25) = crosssum of X(I) and X(J) for these (I,J): (2,20), (3,394), (6,159), (8,329), (63,78), (72,306), (125,525)
X(25) = crossdifference of any two points on line X(441)X(525)
X(25) = X(I)-Hirst inverse of X(J) for these (I,J): (4,419), (6,232)
X(25) = X(I)-beth conjugate of X(J) for these (I,J): (33,33), (108,25), (162,278)


X(26) = CIRCUMCENTER OF THE TANGENTIAL TRIANGLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a[b2cos 2B + c2cos 2C - a2cos 2A]
                         Trilinears        g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = (J2 - 3) cos A + 4 cos B cos C, where J is as at X(1113)

Barycentrics  h(a,b,c) : h(b,c,a) : h(c,a,b), where h(a,b,c) = a2(b2cos 2B + c2cos 2C - a2cos 2A)

If you have The Geometer's Sketchpad, you can view X(26).

Theorems involving X(26), published in 1889 by A. Gob, are discussed in
Roger A. Johnson, Advanced Euclidean Geometry, Dover, 1960, 259-260.

X(26) lies on these lines: 2,3   6,143   52,184   68,161   98,1286   154,155   206,511   1605,1607   1606,1608

X(26) is the {X(154),X(155)}-harmonic conjugate of X(156). For a list of other harmonic conjugates of X(26), click Tables at the top of this page.

X(26) = reflection of X(155) in X(156)
X(26) = isogonal conjugate of X(70)
X(26) = inverse-in-circumcircle of X(2072)
X(26) = crosssum of X(125) and X(924)


X(27) = CEVAPOINT OF ORTHOCENTER AND CLAWSON CENTER

Trilinears       (sec A)/(b + c) : (sec B)/(c + a) : (sec C)/(a + b)
Barycentrics  (tan A)/(b + c) : (tan B)/(c + a) : (tan C)/(a + b)

If you have The Geometer's Sketchpad, you can view X(27).

X(27) lies on these lines:
2,3   6,1246   7,81   19,63   57,273   58,270   84,1896   86,1474   103,107   110,917   226,284   239,1829   243,1859   295,335   306,1043   393,967   579,1751   648,903   662,913   1014,1440   1088,1434   1268,1796   1719,1733   1730,1746   1770,1780

X(27) is the {X(2),X(4)}-harmonic conjugate of X(469). For a list of other harmonic conjugates of X(27), click Tables at the top of this page.

X(27) = isogonal conjugate of X(71)
X(27) = isotomic conjugate of X(306)
X(27) = inverse-in-circumcircle of X(2073)
X(27) = inverse-in-orthocentroidal-circle of X(469)
X(27) = complement of X(3151)
X(27) = anticomplement of X(440)
X(27) = X(286)-Ceva conjugate of X(29)
X(27) = cevapoint of X(I) and X(J) for these (I,J): (4,19), (57,278)
X(27) = X(I)-cross conjugate of X(J) for these (I,J): (4,286), (19,28), (57,81), (58,86)
X(27) = crossdifference of any two points on line X(647)X(810)
X(27) = X(I)-Hirst inverse of X(J) for these (I,J): (2,447), (4,423)
X(27) = X(I)-beth conjugate of X(J) for these (I,J): (648,27), (923,27)


X(28) = CEVAPOINT OF X(19) AND X(25)

Trilinears       (tan A)/(b + c) : (tan B)/(c + a) : (tan C)/(a + b)
Barycentrics  (sin A tan A)/(b + c) : (sin B tan B)/(c + a) : (sin C tan C)/(a + b)

If you have The Geometer's Sketchpad, you can view X(28).

X(28) lies on these lines:
1,19   2,3   10,1891   11,1852   33,975   34,57   35,1869   36,1838   46,1780   54,1243   56,278   60,81   65,1175   72,1257   88,162   104,107   105,112   108,225   110,915   142,1890   228,943   242,261   272,273   279,1014   281,958   291,1783   501,1831   579,1724   580,1730   607,1002   608,959   614,1472   956,1219   957,1191   961,1169   1104,1333   1125,1848   1155,1888   1170,1876   1178,1432   1224,1826   1255,1824   1295,1301   1385,1871   1412,1422   1633,1770   1710,1725

X(28) is the {X(27),X(29)}-harmonic conjugate of X(4). For a list of other harmonic conjugates of X(28), click Tables at the top of this page.

X(28) = isogonal conjugate of X(72)
X(28) = inverse-in-circumcircle of X(2074)
X(28) = X(I)-Ceva conjugate of X(J) for these (I,J): (270,58), (286,81)
X(28) = cevapoint of X(I) and X(J) for these (I,J): (19,25), (34,56)
X(28) = X(I)-cross conjugate of X(J) for these (I,J): (19,27), (58,58)
X(28) = crossdifference of any two points on line X(647)X(656)
X(28) = X(4)-Hirst inverse of X(422)
X(28) = X(I)-beth conjugate of X(J) for these (I,J): (29,29), (107,28), (162,28), (270,28)


X(29) = CEVAPOINT OF INCENTER AND ORTHOCENTER

Trilinears       (sec A)/(cos B + cos C) : (sec B)/(cos C + cos A) : (sec C)/(cos A + cos B)
Barycentrics  (tan A)/(cos B + cos C) : (tan B)/(cos C + cos A) : (tan C)/(cos A + cos B)

If you have The Geometer's Sketchpad, you can view X(29).

X(29) lies on these lines:
1,92   2,3   8,219   10,1794   33,78   34,77   58,162   65,296   81,189   102,107   112,1311   226,951   242,257   270,283   284,950   314,1039   388,1037   392,1871   497,1036   515,947   648,1121   662,1800   758,1844   894,1868   960,1859   1056,1059   1057,1058   1125,1838   1220,1474   1737,1780   1807,1897   1842,1848

X(29) is the {X(3),X(4)}-harmonic conjugate of X(412). For a list of other harmonic conjugates of X(29), click Tables at the top of this page.

X(29) = isogonal conjugate of X(73)
X(29) = isotomic conjugate of X(307)
X(29) = inverse-in-circumcircle of X(2075)
X(29) = complement of X(3152)
X(29) = X(286)-Ceva conjugate of X(27)
X(29) = cevapoint of X(I) and X(J) for these (I,J): (1,4), (33,281)
X(29) = X(I)-cross conjugate of X(J) for these (I,J): (1,21), (284,333), (497,314)
X(29) = crosssum of X(I) and X(J) for these (I,J): (1,1047), (228,1409)
X(29) = crossdifference of any two points on line X(647)X(822)
X(29) = X(4)-Hirst inverse of X(415)
X(29) = X(I)-beth conjugate of X(J) for these (I,J): (29,28), (811,29)


X(30) = EULER INFINITY POINT

Trilinears       cos A - 2 cos B cos C : cos B - 2 cos C cos A : cos C - 2 cos A cos B
                     = 3 cos A - 2 sin B sin C : 3 cos B - 2 sin C sin A : 3 cos C - 2 sin A sin B
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc[2a4 - (b2 - c2)2 - a2(b2 + c2)]

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = 2a4 - (b2 - c2)2 - a2(b2 + c2)

X(30) is the point of intersection of the Euler line and the line at infinity. Thus, each of the lines listed below is parallel to the Euler line.

If you have The Geometer's Sketchpad, you can view Euler Infinity Point.

X(30) lies on the Neuberg cubic and these (parallel) lines:
1,79   2,3   6,2549   7,3488   8,3578   9,3579   10,3579   11,36   12,35   13,15   14,16   33,1060   34,1062   40,191   46,1837   49,1614   50,1989   52,185   53,577   54,3521   55,495   56,496   57,3586   58,1834   61,397   62,398   63,3419   64,68   65,1770   69,3426   74,265   80,484   98,671   99,316   100,2687   101,2688   102,2689   103,2690   104,1290   105,2691   106,2692   107,2693   108,2694   109,2695   110,477  111,2696   112,2697   113,1495   114,2482   115,187   119,2077   133,3184   140,186   141,3098   143,389   146,323   148,385   155,1498   156,1147   182,597   191,355   262,598   265,476   284,1901   298,616   299,617   315,1975   316,325   340,1494   371,3070   372,3071   388,3295   390,1056   485,1151   486,1152   489,638   490,637   497,999   511,512   551,946   553,942   554,1081   568,3060   582,1724   599,1350   618,623   619,624   620,625   671,691   674,680   691,2080   841,1302   935,1297   944,962   946,1385   956,3434   1043,1330   1081,1464   1141,1157   1147,1660   1151,1327   1152,1328   1155,1737   1292,2752   1293,2758   1294,1304   1295,2766   1296,2770   1319,1387   1337,3479   1338,3480   1350,1352   1351,1353   1465,1877   1587,3311   1588,3312   1625,3289   1699,3576   1807,3465   1838,1852   1865,2193   1870,3100   1990,3163   2021,2023   2094,2095   2132,2133   2931,2935   3255,3577   3481,3482

X(30) = orthopoint of X(523)
X(30) = isogonal conjugate of X(74)
X(30) = isotomic conjugate of X(1494)
X(30) = anticomplementary conjugate of X(146)
X(30) = complementary conjugate of X(113)
X(30) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,113), (265,5), (476,523)
X(30) = cevapoint of X(3) and X(399)
X(30) = crosspoint of X(I) and X(J) for these (I,J): (13,14), (94,264)
X(30) = crosssum of X(I) and X(J) for these (I,J): (15,16), (50,184)
X(30) = crossdifference of any two points on line X(6)X(647)


X(31) = 2nd POWER POINT

Trilinears       a2 : b2 : c2
                        = 1 - cos 2A : 1 - cos 2B : 1 - cos 2C

Barycentrics  a3 : b3 : c3

X(31) = (r2 + s2)*X(1) - 6rR*X(2) - 4r2*X(3)   (Peter Moses, April 2, 2013)

If you have The Geometer's Sketchpad, you can view X(31) (1), X(31) (2), X(31) (3).

X(31) lies on these lines:
1,21   2,171   3,601   4,3072   6,42   8,987   9,612   10,964   19,204   25,608   28,2282   32,41   33,2250   34,1254   35,386   36,995   37,2214   40,580   43,100   44,210   48,560   51,181   56,154   57,105   65,1104   72,976   75,82   76,734   86,2296   91,1087   92,162   99,715   101,609   106,2163   110,593   112,2249   158,2190   163,923   165,2999   172,1613   184,604   197,2183   198,2255   199,2277   200,1261   218,1260   222,1458   226,3011   237,904   240,1748   278,1430   284,2258   292,1915   354,1279   388,1935   404,978   497,1936   516,1754   561,722   582,3579   607,2357   649,884   663,2423   669,875   678,3158   692,2877   701,789   708,1502   740,3187   743,825   745,827   759,994   775,1097   872,2220   893,1691   899,1376   901,2382   937,1103   940,1001   982,3218   984,3219   990,1709   999,1149   1066,3157   1098,2363   1124,3076   1182,3192   1210,1771   1331,2991   1335,3077   1393,1454   1403,1428   1427,1456   1438,2279   1450,1470   1474,2215   1486,2260   1572,2170   1582,1740   1616,3304   1633,3123   1820,1953   1836,3120   1910,2186   1911,1922   1917,2085   1927,1967   1932,1973   1951,3010   1974,2281   1979,2107   2003,2078   2054,2248   2083,2156   2153,2154   2188,2638   2242,3230   2264,3198   2274,3286   2318,2911   3074,3085   3075,3086   3220,3415

X(31) is the {X(1),X(63)}-harmonic conjugate of X(38). For a list of other harmonic conjugates of X(31), click Tables at the top of this page.

X(31) = isogonal conjugate of X(75)
X(31) = isotomic conjugate of X(561)
X(31) = anticomplement of X(2887)
X(31) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,48), (6,41), (9,205), (58,6), (82,1)
X(31) = X(213)-cross conjugate of X(6)
X(31) = crosspoint of X(I) and X(J) for these (I,J): (1,19), (6,56)

X(31) = crosssum of X(I) and X(J) for these (I,J): (1,63), (2,8), (7,347), (10,321), (239,1281), (244,514), (307,1441), (523,1086), (693,1111)

X(31) = crossdifference of any two points on line X(514)X(661)
X(31) = X(1403)-Hirst inverse of X(1428)
X(31) = X(I)-aleph conjugate of X(J) for these (I,J): (82,31), (83,75)
X(31) = X(I)-beth conjugate of X(J) for these (I,J): (21,993), (55,55), (109,31), (110,57), (643,31), (692,31)


X(32) = 3rd POWER POINT

Trilinears       a3 : b3 : c3
                        = sin(A - ω) : sin(B - ω) : sin(C - ω)
                        = sin A + sin(A - 2ω) : sin B + sin(B - 2ω) : sin C + sin(C - 2ω)
                        = cos A - cos(A - 2ω) : cos B - cos(B - 2ω) : cos C - cos(C - 2ω) (cf., X(39))

Barycentrics  a4 : b4 : c4

X(32) = -(r2 + 4rR - s2)(r2 + 2rR + s2)*X(1) + 6rR(r2 + 4rR - s2)*X(2) + 2r2(r2 + 4rR - 3s2)*X(3)   (Peter Moses, April 2, 2013)

If you have The Geometer's Sketchpad, you can view X(32).

X(32) lies on these lines:
1,172   2,83   3,6   4,98   5,230   9,987   20,2549   21,981   22,1194   24,232   25,1184   31,41   35,2276   48,1472   51,2351   55,1500   56,1015   71,2273   75,746   76,384   81,980   99,194   100,713   101,595   110,729   111,1383   163,849   165,1571   184,211   218,906   220,3052   262,3406   263,1976   512,878   538,1003   560,1918   561,724   590,640   604,1106   615,639   632,3055   637,3069   638,3068   682,1974   695,3492   710,1502   731,825   733,827   902,1334   904,1933   910,1104   941,1169   958,1572   983,3495   988,1449   993,1107   1009,1724   1055,1201   1084,1576   1092,3289   1191,3207   1204,3269   1376,1574   1395,1402   1423,3500   1468,2280   1613,1915   1843,2353   1911,1932   1919,3249   1922,1923   1950,2285   1951,2082   1992,2482   1995,3291   2004,2005   2319,3494   2508,2881   2698,2715   3087,3088   3124,3457   3170,3171   3497,3512   3499,3511

X(32) is the {X(3),X(6)}-harmonic conjugate of X(39). For a list of other harmonic conjugates of X(32), click Tables at the top of this page.

X(32) = midpoint of X(371) and X(372)
X(32) = reflection of X(315) in X(626)
X(32) = isogonal conjugate of X(76)
X(32) = isotomic conjugate of X(1502)
X(32) = inverse-in-circumcircle of X(1691)
X(32) = inverse-in-Brocard-circle of X(39)
X(32) = inverse-in-1st-Lemoine-circle of X(1692)
X(32) = complement of X(315)
X(32) = anticomplement of X(626)
X(32) = X(I)-Ceva conjugate of X(J) for these (I,J): (2,206), (6,184), (112,512), (251,6)
X(32) = crosspoint of X(I) and X(J) for these (I,J): (2,66), (6,25)

X(32) = crosssum of X(I) and X(J) for these (I,J): (2,69), (6,22), (75,312), (115,826), (311,343), (313,321), (338,850), (339,525), (349,1231), (693,1086), (1229,1233), (1230,1269)

X(32) = crossdifference of any two points on line X(325)X(523)
X(32) = X(184)-Hirst inverse of X(237)
X(32) = X(I)-beth conjugate of X(J) for these (I,J): (41,41), (163,56), (919,32)
X(32) = external center of similitude of circumcircle and Moses circle


X(33) = PERSPECTOR OF THE ORTHIC AND INTANGENTS TRIANGLES

Trilinears       1 + sec A : 1 + sec B : 1 + sec C = tan A cot(A/2) : tan B cot(B/2) : tan C cot(C/2)
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (b + c - a)/(b2 + c2 - a2)
                        = g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sec A cos2(A/2)

Barycentrics  sin A + tan A : sin B + tan B : sin C + tan C
                        = h(A,B,C) : h(B,C,A) : h(C,A,B), where h(A,B,C) = tan A cos2(A/2)

X(33) = (r + 2R - s)(r + 2R + s)*X(1) - 6rR*X(2) + 4rR*X(3)   (Peter Moses, April 2, 2013)

Let LA be the reflection of line BC in the internal angle bisector of angle A, and define LB and LC cyclically. Let DEF be the triangle formed by LA, LB, LC. Then DEF (the intangents triangle) is homothetic to the orthic triangle, and the homothetic center is X(33). (Randy Hutson, 9/23/2011)

If you have The Geometer's Sketchpad, you can view X(33).

X(33) lies on these lines:
1,4   2,1040   5,1062   6,204   7,1041   8,1039   9,212   10,406   11,427   12,235   19,25   20,1038   24,35   28,975   29,78   30,1060   36,378   40,201   42,393   47,90   56,963   57,103   63,1013   64,65   79,1063   80,1061   84,603   112,609   200,281   210,220   222,971   264,350

X(33) is the {X(1),X(4)}-harmonic conjugate of X(34). For a list of other harmonic conjugates, click Tables at the top of this page.

X(33) = isogonal conjugate of X(77)
X(33) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,19), (29,281), (318,9)
X(33) = X(I)-cross conjugate of X(J) for these (I,J): (41,9), (42,55)
X(33) = crosspoint of X(I) and X(J) for these (I,J): (1,282), (4,281)
X(33) = crosssum of X(I) and X(J) for these (I,J): (1,223), (3,222), (57,1394), (73,1214)
X(33) = crossdifference of any two points on line X(652)X(905)
X(33) = X(33)-beth conjugate of X(25)


X(34) = X(4)-BETH CONJUGATE OF X(4)

Trilinears       1 - sec A : 1 - sec B : 1 - sec C
                        = tan A tan(A/2) : tan B tan(B/2) : tan C tan(C/2)
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[(b + c - a)(b2 + c2 - a2)]
                        = g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sec A sin2(A/2)

Barycentrics  sin A - tan A : sin B - tan B : sin C - tan C
                        = h(A,B,C) : h(B,C,A) : h(C,A,B), where h(A,B,C) = tan A sin2(A/2)

X(34) = (r + 2R - s)(r + 2R + s)*X(1) + 6rR*X(2) - 4rR*X(3)   (Peter Moses, April 2, 2013)

X(34) is the center of perspective of the orthic triangle and the reflection in the incenter of the intangents triangle.

If you have The Geometer's Sketchpad, you can view X(34) (1) and X(34) (2).

X(34) lies on these lines:
1,4   2,1038   5,1060   6,19   7,1039   8,1041   9,201   10,475   11,235   12,427   20,1040   24,36   25,56   28,57   29,77   30,1062   35,378   40,212   46,47   55,227   79,1061   80,1063   87,242   106,108   196,937   207,1042   222,942   244,1106   331,870   347,452   860,997

X(34) is the {X(1),X(4)}-harmonic conjugate of X(33). For a list of other harmonic conjugates of X(34), click Tables at the top of this page.

X(34) = isogonal conjugate of X(78)
X(34) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,207), (4,208), (28,56), (273,57), (278,19)
X(34) = X(25)-cross conjugate of X(19)
X(34) = crosssum of X(219) and X(1260)
X(34) = X(56)-Hirst inverse of X(1430)
X(34) = X(I)-beth conjugate of X(J) for these (I,J):
(1,221), (4,4), (28,34), (29,1), (107,158), (108,34), (110,47), (162,34), (811,34)

X(34) = crossdifference of any two points on line X(521)X(652)


X(35) = {X(1),X(3)}-HARMONIC CONJUGATE OF X(36)

Trilinears       1 + 2 cos A : 1 + 2 cos B : 1 + 2 cos C
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a(b2 + c2 - a2 + bc)

Barycentrics  sin A + sin 2A : sin B + sin 2B : sin C + sin 2C
                        = g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = a2(b2 + c2 - a2 + bc)

Let A' be the inverse-in-circumcircle of the A-excenter, and define B' and C' cyclically. Then the lines AA', BB', CC' concur in X(35).

X(35) lies on these lines:
1,3   4,498   8,993   9,90   10,21   11,140   12,30   22,612   24,33   31,386   34,378   37,267   42,58   43,1011   47,212   71,284   72,191   73,74   79,226   172,187   228,846   255,991   376,388   404,1125   411,516   474,1001   495,550   496,549   497,499   500,1154   595,902   950,1006   968,975   1124,1152

If you have The Geometer's Sketchpad, you can view X(35).

X(35) is the {X(1),X(3)}-harmonic conjugate of X(36). For a list of other harmonic conjugates of X(35), click Tables at the top of this page.

X(35) = isogonal conjugate of X(79)
X(35) = inverse-in-circumcircle of X(484)
X(35) = X(500)-cross conjugate of X(1)
X(35) = crosssum of X(481) and X(482)
X(35) = X(943)-aleph conjugate of X(35)
X(35) = X(I)-beth conjugate of X(J) for these (I,J): (100,35), (643,10)


X(36) = INVERSE-IN-CIRCUMCIRCLE OF INCENTER

Trilinears       1 - 2 cos A : 1 - 2 cos B : 1 - 2 cos C
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a(b2 + c2 - a2 - bc)
                   &nbsnbsp;    = g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sec(A/2) cos(3A/2)

Barycentrics  sin A - sin 2A : sin B - sin 2B : sin C - sin 2C
                        = g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = a2(b2 + c2 - a2 - bc)

If you have The Geometer's Sketchpad, you can view X(36).

X(36) is the {X(3),X(56)}-harmonic conjugate of X(1). For a list of other harmonic conjugates of X(36), click Tables at the top of this page.

X(36) lies on these lines:
1,3   2,535   4,499   6,609   10,404   11,30   12,140   15,202   16,203   21,79   22,614   24,34   31,995   33,378   39,172   47,602   48,579   54,73   58,60   59,1110   63,997   80,104   84,90   99,350   100,519   101,672   106,901   109,953   187,1015   191,960   214,758   226,1006   238,513   255,1106   376,497   388,498   474,958   495,549   496,550   573,604   1030,1100

X(36) = midpoint of X(1) and X(484)
X(36) = reflection of X(I) in X(J) for these (I,J): (1,1319), (484,1155)
X(36) = isogonal conjugate of X(80)
X(36) = inverse-in-circumcircle of X(1)
X(36) = inverse-in-incircle of X(942)
X(36) = inverse-in-Bevan-circle of X(46)
X(36) = X(I)-Ceva conjugate of X(J) for these (I,J): (88,6), (104,1)
X(36) = crosspoint of X(58) and X(106)
X(36) = crosssum of X(I) and X(J) for these (I,J): (1,484), (10,519), (11,900)
X(36) = crossdifference of any two points on line X(37)X(650)
X(36) = X(104)-aleph conjugate of X(36)
X(36) = X(I)-beth conjugate of X(J) for these (I,J): (21,36), (100,36), (643,519)


X(37) = CROSSPOINT OF INCENTER AND CENTROID

Trilinears       b + c : c + a : a + b
Trilinears       ar - S : br - S : cr - S
Barycentrics  a(b + c) : b(c + a) : c(a + b)
X(37) = (r2 + 2rR - s2)*X(1) - 6rR*X(2) - 2r2*X(3)   (Peter Moses, April 2, 2013)

Let A'B'C' be the cevian triangle of X(1). Let A" be the centroid of triangle AB'C', and define B" and C" cyclically. Then the lines AA", BB", CC" concur in X(37). (Eric Danneels, Hyacinthos 7892, 9/13/03)

A simple construction of X(37) as a crosspoint can be generalized as follows: let DEF be the medial triangle of ABC and let A'B'C' be the cevian triangle of a point U other than the centroid, X(2). The crosspoint of X(2) and U is then the point of concurrence of lines LD,ME,NF, where L,M,N are the respective midpoints of AA', BB', CC'. If U=u : v : w (trilinears), then crosspoint(X(2),U) = b/w+c/v : c/u+a/w : a/v+b/u, assuming that uvw is nonzero. In particular, if U=X(1), then the crosspoint is X(37). (Seiichi Kirikami, July 10, 2011)

X(37) = perspector of ABC and the medial triangle of the incentral triangle of ABC. (Randy Hutson, August 23, 2011)

X(37) = center of the Hofstadter ellipse E(1/2); see X(359). (Randy Hutson, August 9, 2014)

If you have The Geometer's Sketchpad, you can view X(37).

X(37) lies on these lines:
1,6   2,75   3,975   7,241   8,941   10,594  12,225   19,25   21,172   35,267   38,354   39,596   41,584   48,205   63,940   65,71   73,836   78,965   82,251   86,190   91,498   100,111   101,284   141,742   142,1086   145,391   158,281   171,846   226,440   256,694   347,948   513,876   517,573   537,551   579,942   626,746   665,900   971,991

X(37) is the {X(1),X(9)}-harmonic conjugate of X(6). For a list of other harmonic conjugates of X(37), click Tables at the top of this page.

X(37) = midpoint of X(I) and X(J) for these (I,J): (75,192), (190,335)
X(37) = isogonal conjugate of X(81)
X(37) = isotomic conjugate of X(274)
X(37) = complement of X(75)
X(37) = complementary conjugate of X(2887)

X(37) = X(I)-Ceva conjugate of X(J) for these (I,J):
(1,42), (2,10), (4,209), (9,71), (10,210), (190,513), (226,65), (321,72), (335,518)

X(37) = cevapoint of X(213) and X(228)
X(37) = X(I)-cross conjugate of X(J) for these (I,J): (42,65), (228,72)
X(37) = crosspoint of X(I) and X(J) for these (I,J): (1,2), (9,281), (10,226)
X(37) = X(1)-line conjugate of X(238)
X(37) = crosssum of X(I) and X(J) for these (I,J): (1,6), (57,222), (58,284), (1333,1437)
X(37) = crossdifference of any two points on line X(36)X(238)
X(37) = X(10)-Hirst inverse of X(740)
X(37) = X(1)-aleph conjugate of X(1051)
X(37) = X(I)-beth conjugate of X(J) for these (I,J): (9,37), (644,37), (645,894), (646,37), (1018,37)


X(38) = CROSSPOINT OF X(1) AND X(75)

Trilinears       b2 + c2 : c2 + a2 : a2 + b2
                         = csc A sin(A + ω) : csc B sin(B + ω) : csc C sin(C + ω)
                         = SA + Sω : SB + Sω : SC + Sω

Barycentrics  a(b2 + c2) : b(c2 + a2) : c(a2 + b2)
                        = sin(A + ω) : sin(B + ω) : sin(C + ω)
X(38) = 3r2 + 8rR - s2)*X(1) - 6rR*X(2) - 4r2*X(3)   (Peter Moses, April 2, 2013)

X(38) lies on these lines:
1,21   2,244   3,976   8,986   9,614   10,596   37,354   42,518   56,201   57,612   75,310   78,988   92,240   99,745   210,899   321,726   869,980   912,1064   1038,1106

X(38) is the {X(1),X(63)}-harmonic conjugate of X(31). For a list of other harmonic conjugates of X(38), click Tables at the top of this page.

X(38) = isogonal conjugate of X(82)
X(38) = isotomic conjugate of X(3112)
X(38) = anticomplement of X(1215)
X(38) = crosspoint of X(1) and X(75)
X(38) = crosssum of X(1) and X(31)
X(38) = crossdifference of any two points on line X(661)X(830)
X(38) = X(643)-beth conjugate of X(38)


X(39) = BROCARD MIDPOINT

Trilinears       a(b2 + c2) : b(c2 + a2) : c(a2 + b2)
                        = sin(A + ω) : sin(B + ω) : sin(C + ω)
                        = sin A + sin(A + 2ω) : sin B + sin(B + 2ω) : sin C + sin(C + 2ω)
                        = cos A - cos(A + 2ω) : cos B - cos(B + 2ω) : cos C - cos(C + 2ω)

Barycentrics  a2(b2 + c2) : b2(c2 + a2) : c2(a2 + b2)

X(39) = (r2 + 4rR - s2)*(r2 + 2rR + s2)X(1) - 6rR(r2 + 4rR - s2)*X(2) - 2r2(r2 + 4rR + s2)*X(3)   (Peter Moses, April 2, 2013)

The midpoint of the 1st and 2nd Brocard points, given by trilinears c/b : a/c : b/a and b/c : c/a : a/b. The third and fourth trilinear representations were given by Peter J. C. Moses (10/3/03); cf. X(511), X(32), X(182).

X(39) lies on these lines:
1,291   2,76   3,6   4,232   5,114   9,978   10,730   36,172   37,596   51,237   54,248   83,99   110,755   140,230   141,732   185,217   213,672   325,626   395,618   493,494   512,881   588,589   590,642   597,1084   615,641

X(39) is the {X(3),X(6)}-harmonic conjugate of X(32). For a list of other harmonic conjugates of X(39), click Tables at the top of this page.

Ross Honsberger, Episodes in Nineteenth and Twentieth Century Euclidean Geometry, Mathematical Association of America, 1995. Chapter 10: The Brocard Points.

X(39) = midpoint of X(76) and X(194)
X(39) = isogonal conjugate of X(83)
X(39) = isotomic conjugate of X(308)
X(39) = inverse-in-circumcircle of X(2076)
X(39) = inverse-in-Brocard-circle of X(32)
X(39) = inverse-in-1st-Lemoine-circle of X(2458)
X(39) = complement of X(76)
X(39) = complementary conjugate of X(626)
X(39) = eigencenter of anticevian triangle of X(512)
X(39) = X(I)-Ceva conjugate of X(J) for these (I,J): (2,141), (4,211), (99,512)
X(39) = crosspoint of X(I) and X(J) for these (I,J): (2,6), (141,427)
X(39) = crosssum of X(I) and X(J) for these (I,J): (2,6), (251,1176)
X(39) = crossdifference of every pair of points on line X(23)X(385)


X(40) = BEVAN POINT

Trilinears       cos B + cos C - cos A - 1 : cos C + cos A - cos B - 1 : cos A + cos B - cos C - 1
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = b/(c + a - b) + c/(a + b - c) - a/(b + c - a)
                        = g(A,B,C) : g(B,C,A) : g(C,A,B), where
                        g(A,B,C) = sin2(B/2) + sin2(C/2) - sin2(A/2)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(40) = X(1) - 2X(3) = 2R*X(4) - (r + 4R)*X(9)

If you have The Geometer's Sketchpad, you can view X(40).

X(40) = point of concurrence of the perpendiculars from the excenters to the respective sides
X(40) = circumcenter of the excentral triangle
X(40) = incenter of the extangents triangle if triangle ABC is acute
X(40) = perspector of the excentral and extangents triangles
X(40) = perspector of the excentral and extouch triangles
X(40) = X(4)-of-hexyl-triangle

This point is mentioned in a problem proposal by Benjamin Bevan, published in Leybourn's Mathematical Repository, 1804, p. 18.

X(40) lies on the Darboux cubic and these lines:
1,3   2,926   4,9   6,380   8,20   30,191   31,580   33,201   34,212   42,581   43,970   58,601   64,72   77,947   78,100   80,90   92,412   101,972   108,207   109,255   164,188   190,341   196,208   219,610   220,910   221,223   256,989   376,519   386,1064   387,579   390,938   392,474   511,1045   550,952   595,602   728,1018   936,960   958,1012   978,1050   2130,3354   2131,3472   3182,3346   3183,3347   3348,3353   3355,3473

X(40) is the {X(55),X(65)}-harmonic conjugate of X(1). For a list of other harmonic conjugates of X(40), click Tables at the top of this page.

X(40) = midpoint of X(8) and X(20)
X(40) = reflection of X(I) in X(J) for these (I,J): (1,3), (4,10), (84,1158), (962,946), (1482,1385)
X(40) = isogonal conjugate of X(84)
X(40) = isotomic conjugate of X(309)
X(40) = inverse-in-circumcircle of X(2077)
X(40) = complement of X(962)
X(40) = anticomplement of X(946)
X(40) = X(I)-Ceva conjugate of X(J) for these (I,J): (8,1), (20,1490), (63,9), (347,223)
X(40) = X(I)-cross conjugate of X(J) for these (I,J): (198,223), (221,1)
X(40) = crosspoint of X(I) and X(J) for these (I,J): (329,347)
X(40) = crosssum of X(56) and X(1413)
X(40) = crossdifference of any two points on line X(650)X(1459)
X(40) = X(I)-aleph conjugate of X(J) for these (I,J): (1,978), (2,57), (8,40), (188,1), (556,63)
X(40) = X(I)-beth conjugate of X(J) for these (I,J): (8,4), (40,221), (643,78), (644,728)


X(41) = X(6)-CEVA CONJUGATE OF X(31)

Trilinears       a2(b + c - a) : b2(c + a - b) : c2(a + b - c)
                        = a2cot(A/2) : b2cot(B/2) : c2cot(C/2)
                        = a2(a - s) : b2(b - s) : c2(c - s)

Barycentrics  a3(b + c - a) : b3(c + a - b) : c3(a + b - c)
X(41) = (r + 2R)(r2 + 4rR + s2)*X(1) - 6rR(r + 4R)*X(2) -2r(2 + 4rR - s2)*X(3)   (Peter Moses, April 2, 2013)

If you have The Geometer's Sketchpad, you can view X(41).

X(41) lies on these lines: 1,101   3,218   6,48   9,21   25,42   31,32   37,584   55,220   58,609   65,910   219,1036   226,379   560,872   601,906   603,911   663,884

X(41) is the {X(32),X(213)}-harmonic conjugate of X(31). For a list of other harmonic conjugates of X(41), click Tables at the top of this page.

X(41) = isogonal conjugate of X(85)
X(41) = X(I)-Ceva conjugate of X(J) for these (I,J): (6,31), (9,212), (284,55)
X(41) = crosspoint of X(I) and X(J) for these (I,J): (6,55), (9,33)
X(41) = crosssum of X(I) and X(J) for these (I,J): (1,169), (2,7), (57,77), (92,342), (226,1441), (514,1111)
X(41) = crossdifference of any two points on line X(522)X(693)
X(41) = X(I)-beth conjugate of X(J) for these (I,J): (41,32), (101,41), (220,220)


X(42)  CROSSPOINT OF INCENTER AND SYMMEDIAN POINT

Trilinears       a(b + c) : b(c + a) : c(a + b)
                        = (1 + cos A)(cos B + cos C) : (1 + cos B)(cos C + cos A) : (1 + cos C)(cos A + cos B)

                        = a(ar - S) : b(br - S): c(cr - S)
Barycentrics  a2(b + c) : b2(c + a) : c2(a + b)

If you have The Geometer's Sketchpad, you can view X(42).

X(42) lies on these lines:
1,2   3,967   6,31   9,941   25,41   33,393   35,58   37,210   38,518   40,581   48,197   57,1001   65,73   81,100   101,111   165,991   172,199   181,228   244,354   308,313   321,740   517,1064   560,584   649,788   694,893   748,1001   750,940   894,1045   942,1066

X(42) is the {X(1),X(43)}-harmonic conjugate of X(2). For a list of other harmonic conjugates of X(42), click Tables at the top of this page.

X(42) = reflection of X(321) in X(1215)
X(42) = isogonal conjugate of X(86)
X(42) = isotomic conjugate of X(310)
X(42) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,37), (6,213), (10,71), (55,228)
X(42) = crosspoint of X(I) and X(J) for these (I,J): (1,6), (33,55), (37,65)
X(42) = crosssum of X(I) and X(J) for these (I,J): (1,2), (7,77), (21,81)
X(42) = crossdifference of any two points on line X(239)X(514)
X(42) = X(1)-line conjugate of X(239)
X(42) = X(I)-beth conjugate of X(J) for these (I,J): (21,551), (55,42), (100,226), (210,210), (643,171)


X(43) = X(6)-CEVA CONJUGATE OF X(1)

Trilinears       ab + ac - bc : bc + ba - ca : ca + cb - ab
                        = csc B + csc C - csc A : csc C + csc A - csc B : csc A + csc B - csc C

Barycentrics  a(ab + ac - bc) : b(bc + ba - ca) : c(ca + cb - ab)

X(43) lies on these lines:
1,2   6,87   9,256   31,100   35,1011   40,970   46,851   55,238   57,181   58,979   72,986   75,872   81,750   165,573   170,218   210,984   312,740   518,982

X(43) is the {X(2),X(42)}-harmonic conjugate of X(1). For a list of other harmonic conjugates of X(43), click Tables at the top of this page. X(43) is the external center of similitude of the Bevan circle and Apollonius circle; the internal center is X(1695).

X(43) = reflection of X(1) in X(995)
X(43) = isogonal conjugate of X(87)
X(43) = X(6)-Ceva conjugate of X(1)
X(43) = X(192)-cross conjugate of X(1)
X(43) = crosssum of X(2) and X(330)
X(43) = X(55)-Hirst inverse of X(238)

X(43) = X(I)-aleph conjugate of X(J) for these (I,J):
(1,9), (6,43), (55,170), (100,1018), (174,169), (259,165), (365,1), (366,63), (507,362), (509,57)

X(43) = X(660)-beth conjugate of X(43)


X(44) = X(6)-LINE CONJUGATE OF X(1)

Trilinears       b + c - 2a : c + a - 2b : a + b - 2c
Barycentrics  a(b + c - 2a) : b(c + a - 2b) : c(a + b - 2c)

X(44) = (3r2 + 6rR + s2)*X(1) - 18rR*X(2) - 6r2*X(3)    (Peter Moses, April 2, 2013)

X(44) lies on these lines: 1,6   2,89   10,752   31,210   51,209   65,374   88,679   181,375   190,239   193,344   214,1017   241,651   292,660   354,748   513,649   527,1086   583,992   678,902

X(44) is the {X(1),X(9)}-harmonic conjugate of X(45). For a list of other harmonic conjugates of X(44), click Tables at the top of this page.

X(44) = midpoint of X(I) and X(J) for these (I,J): (190,239), (3218,3257)
X(44) = reflection of X(1279) in X(238)
X(44) = isogonal conjugate of X(88)
X(44) = complement of X(320)
X(44) = X(I)-Ceva conjugate of X(J) for these (I,J): (2,214), (88,1), (104,55)
X(44) = crosspoint of X(I) and X(J) for these (I,J): (1,88), (2,80)
X(44) = crosssum of X(I) and X(J) for these (I,J): (1,44), (6,36), (57,1465)
X(44) = crossdifference of any two points on line X(1)X(513)
X(44) = X(6)-line conjugate of X(1)
X(44) = X(88)-cross conjugate of X(44)
X(44) = X(I)-beth conjugate of X(J) for these (I,J): (9,44), (644,44), (645,239), (44,44)


X(45) = X(9)-BETH CONJUGATE OF X(1)

Trilinears       2b + 2c - a : 2c + 2a - b : 2a + 2b - c
Barycentrics  a(2b + 2c - a) : b(2c + 2a - b) : c(2a + 2b - c)

X(45) = (3r2 + 6rR - s2)*X(1) - 18rR*X(2) - 6r2*X(3)    (Peter Moses, April 2, 2013)

X(45) lies on these lines: 1,6   2,88   53,281   55,678   141,344   198,1030   210,968   346,594

X(45) is the {X(1),X(9)}-harmonic conjugate of X(44). For a list of other harmonic conjugates of X(45), click Tables at the top of this page.

X(45) = isogonal conjugate of X(89)
X(45) = crosssum of X(6) and X(999)
X(45) = X(I)-beth conjugate of X(J) for these (I,J): (9,1), (644,45)


X(46)   X(4)-CEVA CONJUGATE OF X(1)

Trilinears       cos B + cos C - cos A : cos C + cos A - cos B : cos A + cos B - cos C
Barycentrics  a(cos B + cos C - cos A) : b(cos C + cos A - cos B) : c(cos A + cos B - cos C)

X(46) lies on these lines:
1,3   4,90   9,79   10,63   19,579   34,47   43,851   58,998   78,758   80,84   100,224   158,412   169,672   200,1004   218,910   222,227   225,254   226,498   269,1103   404,997   474,960   499,946   595,614   750,975   978,1054

X(46) is the {X(3),X(65)}-harmonic conjugate of X(1). For a list of other harmonic conjugates of X(46), click Tables at the top of this page.

X(46) = reflection of X(I) in X(J) for these (I,J): (1,56), (1479,1210)
X(46) = isogonal conjugate of X(90)
X(46) = inverse-in-Bevan-circle of X(36)
X(46) = X(4)-Ceva conjugate of X(1)
X(46) = crosssum of X(3) and X(1069)
X(46) = X(I)-aleph conjugate of X(J) for these (I,J): (4,46), (174,223), (188,1079), (366,610), (653, 1020)
X(46) = X(100)-beth conjugate of X(46)


X(47) = X(110)-BETH CONJUGATE OF X(34)

Trilinears       cos 2A : cos 2B : cos 2C = f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = a2(a4 + b4 + c4 - 2a2b2 - 2a2c2)
Trilinears        a2 - 2R2 : b2 - 2R2 : c2 - 2R2
Barycentrics  a cos 2A : b cos 2B : c cos 2C

X(47) = (r2 - R2 + s2)*X(1) - 6rR*X(2) - 4r2*X(3)    (Peter Moses, April 2, 2013)

X(47) lies on these lines:
1,21   19,921   33,90   34,46   35,212   36,602   91,92   158,162   171,498   238,499

X(47) is the {X(91),X(92)}-harmonic conjugate of X(564). For a list of other harmonic conjugates of X(47), click Tables at the top of this page.

X(47) = isogonal conjugate of X(91)
X(47) = eigencenter of cevian triangle of X(92)
X(47) = eigencenter of anticevian triangle of X(48)
X(47) = X(92)-Ceva conjugate of X(48)
X(47) = crosssum of X(I) and X(J) for these (I,J): (656,1109)
X(47) = X(275)-aleph conjugate of X(92)
X(47) = X(I)-beth conjugate of X(J) for these (I,J): (110,34), (643,47)
X(47) = trilinear product of X(371) and X(372)


X(48) = CROSSPOINT OF X(1) AND X(63)

Trilinears       sin 2A : sin 2B : sin 2C
                        = f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = tan B + tan C
                        = g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = a2(b2 + c2 - a2)
                        = SBSC - S2 : SCSA - S2 : SASB - S2

Barycentrics  a sin 2A : b sin 2B : c sin 2C

X(48) = (r2 + 4rR2 + 4R2 + s2)*X(1) - 6R(2R + r)*X(2) - 2(r2 + 2rR - s2)*X(3)    (Peter Moses, April 2, 2013)

X(48) lies on these lines:
1,19   3,71   6,41   9,101   31,560   36,579   37,205   42,197   55,154   63,326   75,336   163,1094   184,212   220,963   255,563   281,944   282,947   354,584   577,603   692,911   949,1037   958,965

X(48) is the {X(41),X(604)}-harmonic conjugate of X(6). For a list of other harmonic conjugates of X(48), click Tables at the top of this page.

X(48) = isogonal conjugate of X(92)
X(48) = isotomic conjugate of X(1969)
X(48) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,31), (3,212), (63,255), (92,47), (284, 6)
X(48) = X(228)-cross conjugate of X(3)
X(48) = crosspoint of X(I) and X(J) for these (I,J): (1,63), (3,222), (91,92), (219,268)
X(48) = crosssum of X(I) and X(J) for these (I,J): (1,19), (4,281), (47,48), (196,278), (523, 1146), (661,1109)
X(48) = crossdifference of any two points on line X(240)X(522)
X(48) = X(1)-line conjugate of X(240)
X(48) = X(I)-beth conjugate of X(J) for these (I,J): (101,48), (219,219), (284,604), (906,48)


X(49) = CENTER OF SINE-TRIPLE-ANGLE CIRCLE

Trilinears       cos 3A : cos 3B : cos 3C
Barycentrics  sin A cos 3A : sin B cos 3B : sin C cos 3C

X(49) = (r2 + 2rR2 + s2)*X(1) - 6R(R + r)*X(2) - 3(r2 + 4rR + R2 - s2)*X(3)    (Peter Moses, April 2, 2013)

V. Thebault, "Sine-triple-angle-circle," Mathesis 65 (1956) 282-284.

X(49) lies on these lines: 1,215   3,155   4,156   5,54   24,568   52,195   93,94   381,578

X(49) is the {X(54),X(110)}-harmonic conjugate of X(5). For a list of other harmonic conjugates of X(49), click Tables at the top of this page.

X(49) = isogonal conjugate of X(93)
X(49) = eigencenter of cevian triangle of X(94)
X(49) = eigencenter of anticevian triangle of X(50)
X(49) = X(94)-Ceva conjugate of X(50)


X(50) = X(74)-CEVA CONJUGATE OF X(184)

Trilinears       sin 3A : sin 3B : sin 3C
Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin A + cos A cot D/2, where where cot D/2 = (4*area)/(6R2 - a2 - b2 - c2), where R = abc/(4*area)       (Peter Moses, 12/19/2011; cf. X(568))
Barycentrics  sin A sin 3A : sin B sin 3B : sin C sin 3C

X(50) = -(r2 + 2rR + s2)(r2 + 4rR + 3R2 - s2)*X(1) + 6rR(r2 + 4rR + 3R2 - s2)*X(2) + 2r2(r2 + 4rR + 3R2 - 3s2)*X(3)    (Peter Moses, April 2, 2013)

X(50) lies on these lines: 3,6   67,248   112,477   115,231   230,858   338,401   647,654

X(50) is the {X(3),X(6)}-harmonic conjugate of X(566). For a list of other harmonic conjugates of X(40), click Tables at the top of this page.

X(50) = isogonal conjugate of X(94)
X(50) = inverse-in-Brocard-circle of X(566)
X(50) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,215), (74,184), (94,49)
X(50) = crosspoint of X(I) and X(J) for these (I,J): (93,94), (186,323)
X(50) = crosssum of X(49) and X(50)
X(50) = crossdifference of any two points on line X(5)X(523)
X(50) = barycentric product of X(15) and X(16)


X(51) = CENTROID OF ORTHIC TRIANGLE

Trilinears       a2cos(B - C) : b2cos(C - A) : c2cos(A - B)
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a[a2(b2 + c2) - (b2 - c2)2]

Barycentrics  a3cos(B - C) : b3cos(C - A) : c3cos(A - B)

X(51) = (r2 + 2rR + s2)*X(1) + 6R(R - r)*X(2) - (r2 + 4rR - s2)*X(3)    (Peter Moses, April 2, 2013)

X(51) lies on these lines:
2,262   4,185   5,52   6,25   21,970   22,182   23,575   24,578   26,569   31,181   39,237   44,209   54,288   107,275   125,132   129,137   130,138   199,572   210,374   216,418   381,568   397,462   398,463   573,1011

X(51) is the {X(5),X(143)}-harmonic conjugate of X(52). For a list of other harmonic conjugates of X(51), click Tables at the top of this page.

X(51) = reflection of X(210) in X(375)
X(51) = isogonal conjugate of X(95)
X(51) = complement of X(2979)
X(51) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,53), (5,216), (6,217)
X(51) = X(217)-cross conjugate of X(216)
X(51) = crosspoint of X(I) and X(J) for these (I,J): (4,6), (5,53)
X(51) = crosssum of X(I) and X(J) for these (I,J): (2,3), (6,160), (54,97)
X(51) = crossdifference of any two points on line X(323)X(401)


X(52) = ORTHOCENTER OF ORTHIC TRIANGLE

Trilinears       cos 2A cos(B - C) : cos 2B cos(C - A) : cos 2C cos(A - B)
                        = f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sec A (sec 2B + sec 2C)

Barycentrics  tan A (sec 2B + sec 2C) : tan B (sec 2C + sec 2A) : tan C (sec 2A + sec 2B)

X(52) = (r2 + 2rR + s2)*X(1) - 6rR*X(2) - (r2 - 4rR - 2R2 + s2)*X(3)    (Peter Moses, April 2, 2013)

X(52) lies on these lines:
3,6   4,68   5,51   25,155   26,184   30,185   49,195   113,135   114,211   128,134   129,139

X(52) is the {X(5),X(143)}-harmonic conjugate of X(51). For a list of other harmonic conjugates of X(52), click Tables at the top of this page.

X(52) = reflection of X(I) in X(J) for these (I,J): (3,389), (5,143), (113,1112), (1209,973)
X(52) = isogonal conjugate of X(96)
X(52) = anticomplement of X(1216)
X(52) = inverse-in-Brocard-circle of X(569)
X(52) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,5), (317,467), (324,216)
X(52) = crosspoint of X(4) and X(24)
X(52) = crosssum of X(3) and X(68)


X(53) = SYMMEDIAN POINT OF ORTHIC TRIANGLE

Trilinears       tan A cos(B - C) : tan B cos(C - A) : tan C cos(A - B)
Barycentrics  a tan A cos(B - C) : b tan B cos(C - A) : c tan C cos(A - B)

X(53) lies on these lines:
4,6   5,216   25,157   30,577   45,281   115,133   128,139   137,138   141,264   232,427   273,1086   275,288   311,324   317,524   318,594   395,472   396,473

X(53) is the {X(4),X(393)}-harmonic conjugate of X(6). For a list of other harmonic conjugates of X(53), click Tables at the top of this page.

X(53) = isogonal conjugate of X(97)
X(53) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,51), (324,5)
X(53) = X(51)-cross conjugate of X(5)
X(53) = crosssum of X(3) and X(577)


X(54) = KOSNITA POINT

Trilinears       sec(B - C) : sec(C - A) : sec(A - B)
Barycentrics  sin A sec(B - C) : sin B sec(C - A) : sin C sec(A - B)

John Rigby, "Brief notes on some forgotten geometrical theorems," Mathematics and Informatics Quarterly 7 (1997) 156-158.

Let O be the circumcenter of triangle ABC, and OA the circumcenter of triangle BOC. Define OB and OC cyclically. Then the lines AOA, BOB, COC concur in X(54). For details and generalization, see

Darij Grinberg, A New Circumcenter Question

The above construction of X(54) generalizes. Suppose that P and Q are points (as functions of a,b,c). Let A' = Q-of-BCP, B' = Q-of-CAP, C' = Q-of-ABP. If the lines AA', BB', CC' concur, the perspector is called the Kosnita(P,Q) point, denoted by K(P,Q). (Randy Hutson, 9/23/2011)

X(3) = K(X(20),X(2)) X(4) = K(X(20,X(20) X(5) = K(X(4),X(2))
X(13) = K(X(10),X(1)) X(17) = K(X(13),X(3)) X(18) = K(X(14),X(3))
X(140) = K(X(3), X(2)) X(251) = K(X(6), X(6))
X(481) = K(X(175),X(1)) X(482) = K(X(176),X(1))


X(54) lies on the Napoleon cubic and these lines:
1,3460   2,68   3,97   4,184   5,49   6,24   12,215   36,73   39,248   51,288   64,378   69,95   71,572   72,1006   74,185   112,217   140,252   156,381   186,389   276,290   575,895   826,879   3336,3468

X(54) is the {X(5),X(49)}-harmonic conjugate of X(110). For a list of other harmonic conjugates of X(54), click Tables at the top of this page.

X(54) = midpoint of X(3) and X(195)
X(54) = reflection of X(195) in X(1493)
X(54) = isogonal conjugate of X(5)
X(54) = isotomic conjugate of X(311)
X(54) = inverse-in-circumcircle of X(1157)
X(54) = complement of X(2888)
X(54) = anticomplement of X(1209)
X(54) = X(I)-Ceva conjugate of X(J) for these (I,J): (5,2120), (95,97), (288,6)
X(54) = cevapoint of X(6) and X(184)
X(54) = X(I)-cross conjugate of X(J) for these (I,J): (3,96), (6,275), (186,74), (389,4), (523,110)
X(54) = crosspoint of X(95) and X(275)
X(54) = crosssum of X(I) and X(J) for these (I,J): (3,195), (51,216), (627,628)


X(55) = INSIMILICENTER(CIRCUMCIRCLE, INCIRCLE)

Trilinears       a(b + c - a) : b(c + a - b) : c(a + b - c)
                        = 1 + cos A : 1 + cos B : 1 + cos C
                        = cos2(A/2) : cos2(B/2) : cos2(B/2)
                        = tan(B/2) + tan(C/2) : tan(C/2) + tan(A/2) : tan(A/2) + tan(B/2)
                        = a(a - s) : b(b - s) : c(c - s)

Barycentrics  a2(b + c - a) : b2(c + a - b) : c2(a + b - c)

X(55) = R*X(1) + r*X(3)

X(55) = center of homothety of three triangles:   tangential, intangents, and extangents. Also, X(55) is the pole-with-respect-to-the-circumcircle of the trilinear polar of X(1). These properties and others are given in

O. Bottema and J. T. Groenman, "De gemene raaklijnen van de vier raakcirkels van een driehoek, twee aan twee," Nieuw Tijdschrift voor Wiskunde 67 (1979-80) 177-182.

X(55) lies on these lines:
1,3   2,11   4,12   5,498   6,31   8,21   9,200   10,405   15,203   16,202   19,25   20,388   30,495   34,227   41,220   43,238   45,678   48,154   63,518   64,73   77,1037   78,960   81,1002   92,243   103,109   104,1000   108,196   140,496   181,573   182,613  183,350   184,215   192,385   199,1030   201,774   204,1033   219,284   226,516   255,601   256,983   329,1005   376,1056   386,595   392,997   411,962   511,611   515,1012   519,956   574,1015   603,963   631,1058   650,884   654,926   748,899   840,901   846,984   869,893   1026,1083   1070,1076   1072,1074

X(55) is the {X(1),X(3)}-harmonic conjugate of X(56). For a list of other harmonic conjugates of X(55), click Tables at the top of this page.

X(55) = reflection of X(I) in X(J) for these (I,J): (1478,495), (2099,1)
X(55) = isogonal conjugate of X(7)
X(55) = inverse-in-circumcircle of X(1155)
X(55) = complement of X(3434)
X(55) = anticomplement of X(2886)
X(55) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,6), (3,198), (7,218), (8,219), (9,220), (21,9), (59,101), (104,44), (260,259), (284,41)
X(55) = cevapoint of X(42) and X(228) for these (I,J)
X(55) = X(I)-cross conjugate of X(J) for these (I,J): (41,6), (42,33), (228,212)
X(55) = crosspoint of X(I) and X(J) for these (I,J): (1,9), (3,268), (7,277), (8,281), (21,284), (59,101)

X(55) = crosssum of X(I) and X(J) for these (I,J): (1,57), (2,145), (4,196), (11,514), (55,218), (56,222), (63,224), (65,226), (81,229), (177,234), (241,1362), (513,1086), (905,1364), (1361,1465)

X(55) = crossdifference of any two points on line X(241)X(514)
X(55) = X(I)-Hirst inverse of X(J) for these (I,J): (6,672), (43,241)
X(55) = X(1)-line conjugate of X(241)
X(55) = X(I)-beth conjugate of X(J) for these (I,J): (21,999), (55,31), (100,55), (200,200), (643,2), (1021,1024)


X(56) = EXSIMILICENTER(CIRCUMCIRCLE, INCIRCLE)

Trilinears       a/(b + c - a) : b/(c + a - b) : c/(a + b - c)
                        = 1 - cos A : 1 - cos B : 1 - cos C
                        = sin2(A/2) : sin2(B/2) : sin2(C/2)

Barycentrics  a2/(b + c - a) : b2/(c + a - b) : c2/(a + b - c)

X(56) = R*X(1) - r*X(3)

The perspector of the tangential triangle and the reflection of the intangents triangle in X(1).

X(56) lies on these lines:
1,3   2,12   4,11   5,499   6,41   7,21   8,404   10,474   19,207   20,497   22,977   25,34   28,278   30,496   31,154   32,1015   33,963   38,201   58,222   61,202   62,203   63,960   72,997   77,1036   78,480   81,959   85,870   87,238   100,145   101,218   105,279   106,109   140,495   181,386   182,611   197,227   212,939   219,579   220,672   223,937   226,405   255,602   266,289   269,738   330,385   376,1058   411,938   511,613   551,553   607,911   631,1056   667,764   946,1012   978,979   1025,1083   1070,1074   1072,1076

X(56) is the {X(1),X(3)}-harmonic conjugate of X(55). For a list of other harmonic conjugates of X(56), click Tables at the top of this page.

X(56) = homothetic center of the intouch triangle and the circumcevian triangle of X(1)

X(56) = midpoint of X(1) and X(46)
X(56) = reflection of X(I) in X(J) for these (I,J): (1479,496), (2099,1)
X(56) = isogonal conjugate of X(8)
X(56) = inverse-in-circumcircle of X(1319)
X(56) = complement of X(3436)
X(56) = anticomplement of X(1329)
X(56) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,221), (7,222), (28,34), (57,6), (59,109), (108,513)
X(56) = X(31)-cross conjugate of X(6)
X(56) = crosspoint of X(I) and X(J) for these (I,J): (1,84), (7,278), (28,58), (57,269), (59,109)

X(56) = crosssum of X(I) and X(J) for these (I,J): (1,40), (2,144), (6,197), (9,200), (10,72), (11,522), (55,219), (175,176), (519,1145)

X(56) = crossdifference of any two points on line X(522)X(650)
X(56) = X(I)-Hirst inverse of X(J) for these (I,J): (6,1458), (34,1430), (57,1429), (604,1428), (1416,1438)
X(56) = X(266)-aleph conjugate of X(1050)
X(56) = X(I)-beth conjugate of X(J) for these (I,J):
(1,1), (21,3), (56,1106), (58,56), and (P,57) for all P on the circumcircle


X(57)  ISOGONAL CONJUGATE OF X(9)

Trilinears       1/(b + c - a) : 1/(c + a - b) : 1/(a + b - c)
                        = tan(A/2) : tan(B/2) : tan(C/2)
                        = f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1 + cos B + cos C - cos A
                        = g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = 1 + sin(A/2)csc(B/2)csc(C/2)
                        = h(A,B,C) : h(B,C,A) : h(C,A,B), where h(A,B,C) = cos2(B/2) + cos2(C/2) - cos2(A/2)
                        = SA - bc : SB - ca : SC - ab

Barycentrics  a/(b + c - a) : b/(c + a - b) : c/(a + b - c)

X(57) is the perspector of the intouch triangle and excentral triangle.

X(57) lies on the Thomson cubic and these lines:
1,3   2,7   4,84   6,222   10,388   19,196   20,938   27,273   28,34   31,105   33,103   38,612   42,1002   43,181   72,474   73,386   77,81   78,404   79,90   85,274   88,651   92,653   164,177   169,277   173,174   200,518   201,975   234,362   239,330   255,580  279,479   282,3343   345,728   497,516   499,920   649,1024   658,673   748,896   758,997   955,991   957,995   959,1042   961,1106   978,1046   1020,1086   1073,3351   3342,3350

X(57) is the {X(2),X(7)}-harmonic conjugate of X(226). For a list of other harmonic conjugates of X(57), click Tables at the top of this page.

X(57) = midpoint of X(497) and X(3474)
X(57) = reflection of X(I) in X(J) for these (I,J): (1,999), (200,1376)
X(57) = isogonal conjugate of X(9)
X(57) = isotomic conjugate of X(312)
X(57) = inverse-in-circumcircle of X(2078)
X(57) = inverse-in-Bevan-circle of X(1155)
X(57) = complement of X(329)
X(57) = anticomplement of X(3452)

X(57) = X(I)-Ceva conjugate of X(J) for these (I,J):
(2,223), (7,1), (27,278), (81,222), (85,77), (273,34), (279,269)

X(57) = cevapoint of X(I) and X(J) for these (I,J): (6,56), (19,208)
X(57) = X(I)-cross conjugate of X(J) for these (I,J): (6,1), (19,84), (56,269), (65,7)
X(57) = crosspoint of X(I) and X(J) for these (I,J): (2,189), (7,279), (27,81), (85,273)

X(57) = crosssum of X(I) and X(J) for these (I,J): (1,165), (6,198), (31,205), (37,71), (41,212), (55,220), (210,1334)

X(57) = crossdifference of any two points on line X(650)X(663)
X(57) = X(I)-Hirst inverse of X(J) for these (I,J): (1,241), (7,1447), (56,1429), (105,1462), (910,1419)

X(57) = X(I)-aleph conjugate of X(J) for these (I,J):
(2,40), (7,57), (57,978), (174,1), (366,165), (507,503), (508,9), (509,43)

X(57) = X(I)-beth conjugate of X(J) for these (I,J):
(2,2), (81,57), (88,57), (100,57), (110,31), (162,57), (190,57), (333,63), (648,92), (651,57), (653,57), (655,57), (658,57), (660,57), (662,57), (673,57), (771,57), (799,57), (823,57), (897, 57)


X(58)  ISOGONAL CONJUGATE OF X(10)

Trilinears       a/(b + c) : b/(c + a) : c/(a + b)
Trilinears       sa2 + SR : sb2 + SR : sc2 + SR
Barycentrics  a2/(b + c) : b2/(c + a) : c2/(a + b)

X(58) is the point of concurrence of the Brocard axes of triangles BIC, CIA, AIB, ABC, (where I denotes the incenter, X(1)), as proved in

Antreas P. Hatzipolakis, Floor van Lamoen, Barry Wolk, and Paul Yiu, Concurrency of Four Euler Lines, Forum Geometricorum 1 (2001) 59-68.

X(58) lies on these lines:
1,21   2,540   3,6   7,272   8,996   9,975   10,171   20,387   25,967   27,270   28,34   29,162   35,42   36,60   40,601   41,609   43,979   46,998   56,222   65,109   82,596   84,990   86,238   87,978   99,727   101,172   103,112   106,110   229,244   269,1014   274,870   314,987   405,940   519,1043   942,1104   977,982   1019,1027

X(58) is the {X(3),X(6)}-harmonic conjugate of X(386). For a list of other harmonic conjugates of X(58), click Tables at the top of this page.

X(58) = isogonal conjugate of X(10)
X(58) = isotomic conjugate of X(313)
X(58) = inverse-in-circumcircle of X(1326)
X(58) = inverse-in-Brocard-circle of X(386)
X(58) = complement of X(1330)
X(58) = anticomplement of X(3454)
X(58) = X(I)-Ceva conjugate of X(J) for these (I,J): (81,284), (267,501), (270,28)
X(58) = cevapoint of X(6) and X(31)
X(58) = X(I)-cross conjugate of X(J) for these (I,J): (6,81), (36,106), (56,28), (513,109)
X(58) = crosspoint of X(I) and X(J) for these (I,J): (1,267), (21,285), (27,86), (60,270)
X(58) = crosssum of X(I) and X(J) for these (I,J): (1,191), (6,199), (12,201), (37,210), (42,71), (65,227), (594, 756)
X(58) = crossdifference of any two points on line X(523)X(661)
X(58) = X(6)-Hirst inverse of X(1326)
X(58) = X(I)-beth conjugate of X(J) for these (I,J): (21,21), (60,58), (110,58), (162,58), (643,58), (1098,283)


X(59)  ISOGONAL CONJUGATE OF X(11)

Trilinears       1/[1 - cos(B - C)] : 1/[1 - cos(C - A)] : 1/[1 - cos(A - B)]
Barycentrics  a/[1 - cos(B - C)] : b/[1 - cos(C - A)] : c/[1 - cos(A - B)]

X(59) lies on these lines: 36,1110   60,1101   100,521   101,657   109,901   513,651   518,765   523,655

X(59) = isogonal conjugate of X(11)
X(59) = cevapoint of X(I) and X(J) for these (I,J): (55,101), (56,109)
X(59) = X(I)-cross conjugate of X(J) for these (I,J): (1,110), (3,100), (55,101), (56,109), (182,1492)
X(59) = X(765)-beth conjugate of X(765)


X(60) = ISOGONAL CONJUGATE OF X(12)

Trilinears       1/[1 + cos(B - C)] : 1/[1 + cos(C - A)] : 1/[1 + cos(A - B)]
Barycentrics  a/[1 + cos(B - C)] : b/[1 + cos(C - A)] : c/[1 + cos(A - B)]

X(60) lies on these lines: 1,110   21,960   28,81   36,58   59,1101   86,272   283,284   404,662   757,1014

X(60) = isogonal conjugate of X(12)
X(60) = X(58)-cross conjugate of X(270)
X(60) = X(I)-beth conjugate of X(J) for these (I,J): (60,849), (1098,1098)


X(61) = ISOGONAL CONJUGATE OF X(17)

Trilinears       sin(A + π/6) : sin(B + π/6) : sin(C + π/6)
                        = cos(A - π/3) : cos(B - π/3) : cos(C - π/3)

Barycentrics  sin A sin(A + π/6) : sin B sin(B + π/6) : sin C sin(C + π/6)

X(61) lies on the Napoleon cubic and these lines:
1,203   2,18   3,6   4,13   5,14   30,397   56,202   140,395   299,636   302,629   618,627

X(61) is the {X(3),X(6)}-harmonic conjugate of X(62). For a list of other harmonic conjugates of X(61), click Tables at the top of this page.

X(61) = reflection of X(633) in X(635)
X(61) = isogonal conjugate of X(17)
X(61) = inverse-in-Brocard-circle of X(62)
X(61) = complement of X(633)
X(61) = anticomplement of X(635)
X(61) = eigencenter of cevian triangle of X(14)
X(61) = eigencenter of anticevian triangle of X(16)
X(61) = X(14)-Ceva conjugate of X(16)
X(61) = crosspoint of X(302) and X(473)


X(62) = ISOGONAL CONJUGATE OF X(18)

Trilinears       sin(A - π/6) : sin(B - π/6) : sin(C - π/6)
                        = cos(A + π/3) : cos(B + π/3) : cos(C + π/3)

Barycentrics  sin A sin(A - π/6) : sin B sin(B - π/6) : sin C sin(C - π/6)

X(62) lies the Napoleon cubic and these lines:
1,202   2,17   3,6   4,14   5,13   30,398   56,203   140,396   298,635   303,630   619,628

X(62) is the {X(3),X(6)}-harmonic conjugate of X(61). For a list of other harmonic conjugates of X(62), click Tables at the top of this page.

X(62) = reflection of X(634) in X(636)
X(62) = isogonal conjugate of X(18)
X(62) = inverse-in-Brocard-circle of X(61)
X(62) = complement of X(634)
X(62) = anticomplement of X(636)
X(62) = eigencenter of cevian triangle of X(13)
X(62) = eigencenter of anticevian triangle of X(15)
X(62) = X(13)-Ceva conjugate of X(15)
X(62) = crosspoint of X(303) and X(472)


X(63) = ISOGONAL CONJUGATE OF X(19)

Trilinears       cot A : cot B : cot C
                        = b2 + c2 - a2 : c2 + a2 - b2 : a2 + b2 - c2
                        = SA : SB : SC

Barycentrics  cos A : cos B : cos C

X(63) = (r + 2R)*X(1) - 3R*X(2) - 2r*X(3)    (Peter Moses, April 2, 2013)

X(63) lies on these lines:
1,21   2,7   3,72   8,20   10,46   19,27   33,1013   36,997   37,940   48,326   55,518   56,960   65,958   69,71   77,219   91,921   100,103   162,204   169,379   171,612   190,312   194,239   201,603   210,1004   212,1040   213,980   220,241   223,651   238,614   240,1096   244,748   304,1102   318,412   354,1001   392,999   404,936   405,942   452,938   484,535   517,956   544,1018   561,799   654,918   750,756

X(63) is the {X(9),X(57)}-harmonic conjugate of X(2). For a list of other harmonic conjugates of X(63), click Tables at the top of this page.

X(63) = reflection of X(I) in X(J) for these (I,J): (1,993), (1478,10)
X(63) = isogonal conjugate of X(19)
X(63) = isotomic conjugate of X(92)
X(63) = anticomplement of X(226)
X(63) = anticomplementary conjugate of X(2893)
X(63) = X(I)-Ceva conjugate of X(J) for these (I,J): (7,224), (69,78), (75,1), (304,326), (333,2), (348,77)
X(63) = cevapoint of X(I) and X(J) for these (I,J): (3,219), (9,40), (48,255), (71,72)
X(63) = X(I)-cross conjugate of X(J) for these (I,J): (3,77), (9,271), (48,1), (71,3), (72,69), (219,78), (255,326)
X(63) = crosspoint of X(I) and X(J) for these (I,J): (69,348), (75,304)
X(63) = crosssum of X(25) and X(607)
X(63) = crossdifference of any two points on line X(661)X(663)

X(63) = X(I)-aleph conjugate of X(J) for these (I,J):
(2,1), (75,63), (92,920), (99,662), (174,978), (190,100), (333,411), (366,43), (514,1052), (556,40), (648,162), (664,651), (668,190), (670,799), (671,897), (903,88)

X(63) = X(I)-beth conjugate of X(J) for these (I,J):
(63,222), (190,63), (333,57), (345,345), (643,63), (645,312), (662,223)


X(64) = ISOGONAL CONJUGATE OF X(20)

Trilinears   &nbnbsp;   1/(cos A - cos B cos C) : 1/(cos B - cos C cos A) : 1/(cos C - cos A cos B)
Barycentrics  a/(cos A - cos B cos C) : b/(cos B - cos C cos A) : c/(cos C - cos A cos B)

A construction of X(64) appears in Lemoine's 1886 paper cited at X(19).

X(64) lies on the Darboux cubic and these lines:
1,3182   3,154   4,3183   6,185   20,69   24,74   30,68   33,65   40,72   54,378   55,73   71,198   84,3353   265,382   3345,3472   3346,3355

X(64) = reflection of X(1498) in X(3)
X(64) = isogonal conjugate of X(20)
X(64) = anticomplement of X(2883)
X(64) = X(25)-cross conjugate of X(6)
X(64) = X(1)-beth conjugate of X(207)


X(65) = ORTHOCENTER OF THE INTOUCH TRIANGLE

Trilinears       cos B + cos C : cos C + cos A : cos A + cos B
                        = (b + c)/(b + c - a) : (c + a)/(c + a - b) : (a + b)/(a + b - c)
                        = sin(A/2) cos(B/2 - C/2) : sin(B/2) cos(C/2 - A/2) : sin(C/2) cos(A/2 - B/2)

Barycentrics  a(b + c)/(b + c - a) : b(c + a)/(c + a - b) : c(a + b)/(a + b - c)

X(65) is the perspector of ABC and the extangents triangle.

X(65) lies on these lines:
1,3   2,959   4,158   6,19   7,8   10,12   11,117   29,296   31,1104   33,64   37,71   41,910   42,73   44,374   58,109   63,958   68,91   74,108   77,969   79,80   81,961   110,229   169,218   172,248   224,1004   225,407   243,412   257,894   278,387   279,1002   386,994   409,1098   474,997   497,938   516,950   519,553   604,1100   651,895   1039,1041   1061,1063

X(65) is the {X(1),X(40)}-harmonic conjugate of X(55). For a list of other harmonic conjugates of X(65), click Tables at the top of this page.

X(65) = reflection of X(I) in X(J) for these (I,J): (1,942), (72,10)
X(65) = isogonal conjugate of X(21)
X(65) = isotomic conjugate of X(314)
X(65) = inverse-in-incircle of X(1319)
X(65) = anticomplement of X(960)
X(65) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,73), (4,225), (7,226), (10,227), (109,513), (226,37)
X(65) = X(42)-cross conjugate of X(37)
X(65) = crosspoint of X(I) and X(J) for these (I,J): (1,4), (7,57)
X(65) = crosssum of X(I) and X(J) for these (I,J): (1,3), (9,55), (56,1394)
X(65) = crossdifference of any two points on line X(521)X(650)
X(65) = X(1284)-Hirst inverse of X(1400)
X(65) = X(I)-beth conjugate of X(J) for these (I,J):
(1,65), (8,72), (10,10), (65,1042), (80,65), (100,65), (101,213), (291,65), (668,65), (1018, 65)


X(66) = ISOGONAL CONJUGATE OF X(22)

Trilinears       bc/(b4 + c4 - a4) : ca/(c4 + a4 - b4) : ab/(a4 + b4 - c4)
Barycentrics  1/(b4 + c4 - a4) : 1/(c4 + a4 - b4) : 1/(a4 + b4 - c4)

X(66) lies on these lines:
2,206   3,141   6,427   68,511   73,976   193,895   248,571   290,317   879,924

X(66) = midpoint of X(2892) and X(3448)
X(66) = reflection of X(I) in X(J) for these (I,J): (159,141), (1177,125)
X(66) = isogonal conjugate of X(22)
X(66) = isotomic conjugate of X(315)
X(66) = cyclocevian conjugate of X(2998)
X(66) = anticomplement of X(206)
X(66) = cevapoint of X(125) and X(512)
X(66) = X(32)-cross conjugate of X(2)
X(66) = crosssum of X(3) and X(159)


X(67) = ISOGONAL CONJUGATE OF X(23)

Trilinears       bc/(b4 + c4 - a4 - b2c2) : ca/(c4 + a4 - b4 - c2a2) : ab/(a4 + b4 - c4 - a2b2)
Barycentrics  1/(b4 + c4 - a4 - b2c2) : 1/(c4 + a4 - b4 - c2a2) : 1/(a4 + b4 - c4 - a2b2)

X(67) lies on these lines:
3,542   4,338   6,125   50,248   74,935   110,141   265,511   290,340   524,858   526,879

X(67) = midpoint of X(69) and X(3448)
X(67) = reflection of X(I) in X(J) for these (I,J): (6,125), (110,141)
X(67) = isogonal conjugate of X(23)
X(67) = isotomic conjugate of X(316)
X(67) = inverse-in-circumcircle of X(3455)
X(67) = cevapoint of X(141) and X(524)
X(67) = X(187)-cross conjugate of X(2)


X(68)  PRASOLOV POINT

Trilinears       cos A sec 2A : cos B sec 2B : cos C sec 2C
Barycentrics  tan 2A : tan 2B : tan 2C

Let A'B'C' be the reflection of the orthic triangle of ABC in X(5). The lines AA', BB', CC' concur in X(68), as proved in

V. V. Prasolov, Zadachi po planimetrii, Moscow, 4th edition, 2001.

Coordinates for X(68) can be obtained easily from the Ceva ratios given his Prasolov's proof of concurrence.

X(68) lies on these lines:
2,54   3,343   4,52   5,6   11,1069   20,74   26,161   30,64   65,91   66,511   73,1060   136,254   290,315   568,973

X(68) = reflection of X(155) in X(5)
X(68) = isogonal conjugate of X(24)
X(68) = isotomic conjugate of X(317)
X(68) = anticomplement of X(1147)
X(68) = X(96)-Ceva conjugate of X(3)
X(68) = cevapoint of X(I) and X(J) for these (I,J): (6,161), (125,520)
X(68) = X(115)-cross conjugate of X(525)


X(69) = SYMMEDIAN POINT OF THE ANTICOMPLEMENTARY TRIANGLE

Trilinears       (cos A)/a2 : (cos B)/b2 : (cos C)/c2
                        = bc(b2 + c2 - a2) : ca(c2 + a2 - b2) : ab(a2 + b2 - c2)

Barycentrics  cot A : cot B : cot C
                        = b2 + c2 - a2 : c2 + a2 - b2 : a2 + b2 - c2

X(69) = 2(r2 + 2rR + s2)*X(1) + 3(r2 - s2)*X(2) - 4r2*X(3)    (Peter Moses, April 2, 2013)

X(69) lies on these lines:
2,6   3,332   4,76   7,8   9,344   10,969   20,64   22,159   54,95   63,71   72,304   73,77   74,99   110,206   125,895   144,190   150,668   189,309   192,742   194,695   200,269   248,287   263,308   265,328   274,443   290,670   297,393   347,664   350,497   404,1014   478,651   485,639   486,640   520,879

X(69) is the {X(7),X(8)}-harmonic conjugate of X(75). For a list of other harmonic conjugates of X(69), click Tables at the top of this page.

X(69) is the perspector of the orthic-of-medial triangle and the reference triangle. (Cesar Lozada, November 29, 2010)
X(69) is the perspector of ABC and the pedal triangle of X(20). (Randy Hutson, August 23, 2011)
X(69) is the perspector of ABC and (reflection in X(2) of the pedal triangle of X(2)). (Randy Hutson, August 23, 2011)

If you have The Geometer's Sketchpad, you can view X(69).

X(69) = reflection of X(I) in X(J) for these (I,J): (2,599), (4,1352), (6,141), (20,1350), (193,6), (895,125), (1351,5), (1353,140)

X(69) = isogonal conjugate of X(25)
X(69) = isotomic conjugate of X(4)
X(69) = cyclocevian conjugate of X(253)
X(69) = complement of X(193)
X(69) = anticomplement of X(6)
X(69) = anticomplementary conjugate of X(2)
X(69) = X(I)-Ceva conjugate of X(J) for these (I,J): (76,2), (304,345), (314,75), (332,326)
X(69) = cevapoint of X(I) and X(J) for these (I,J): (2,20), (3,394), (6,159), (8,329), (63,78), (72,306), (125,525)

X(69) = X(I)-cross conjugate of X(J) for these (I,J):
(3,2), (63,348), (72,63), (78,345), (125,525), (306,304), (307,75), (343,76)

X(69) = crosspoint of X(I) and X(J) for these (I,J): (76,305), (314,332)
X(69) = X(2)-Hirst inverse of X(325)
X(69) = X(I)-beth conjugate of X(J) for these (I,J): (69,77), (99,347), (314,7), (332,69), (645,69), (668,69)


X(70) = ISOGONAL CONJUGATE OF X(26)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc/[b2 cos 2B + c2 cos 2C - a2 cos 2A]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = 1/[b2 cos 2B + c2 cos 2C - a2 cos 2A]

X(70) lies on this line: 74,1288

X(70) = isogonal conjugate of X(26)


X(71) = ISOGONAL CONJUGATE OF X(27)

Trilinears       (b + c) cos A : (c + a) cos B : (a + b) cos C
Barycentrics  (b + c) sin 2A : (c + a) sin 2B : (a + b) sin 2C

X(71) lies on these lines:
1,579   3,48   4,9   6,31   35,284   37,65   54,572   63,69   64,198   74,101   165,610   190,290   583,1100

X(71) is the {X(9),X(40)}-harmonic conjugate of X(19). For a list of other harmonic conjugates of X(71), click Tables at the top of this page.

X(71) = isogonal conjugate of X(27)
X(71) = X(I)-Ceva conjugate of X(J) for these (I,J): (3,228), (9, 37), (10,42), (63,72)
X(71) = X(228)-cross conjugate of X(73)
X(71) = crosspoint of X(I) and X(J) for these (I,J): (3,63), (9,219), (10,306)
X(71) = crosssum of X(I) and X(J) for these (I,J): (1,579), (4,19), (28,1127), (57,278), (58,1474)
X(71) = crossdifference of any two points on line X(242)X(514)
X(71) = X(4)-line conjugate of X(242)
X(71) = X(I)-beth conjugate of X(J) for these (I,J): (219,71), (1018,71)


X(72) = ISOGONAL CONJUGATE OF X(28)

Trilinears       (b + c) cot A : (c + a) cot B : (a + b) cot C
                        = (b + c)(b2 + c2 - a2) : (c + a)(c2 + a2 - b2) : (a + b)(a2 + b2 - c2)

Barycentrics  (b + c) cos A : (c + a) cos B : (a + b) cos C

X(72) = (r + 2R)*X(1) - 3R*X(2) - r*X(3)    (Peter Moses, April 2, 2013)

X(72) lies on these lines:
1,6   2,942   3,63   4,8   5,908   7,443   10,12   20,144   21,943   31,976   35,191   40,64   43,986   54,1006   56,997   57,474   69,304   73,201   74,100   145,452   171,1046   185,916   190,1043   222,1038   248,293   290,668   295,337   306,440   394,1060   519,950   672,1009   894,1010   940,975   978,982

X(72) is the {X(1),X(9)}-harmonic conjugate of X(405). For a list of other harmonic conjugates of X(72), click Tables at the top of this page.

X(72) is the perspector of the extouch triangle and the triangle formed by the lines through the external pairs of extouch points. (Randy Hutson, August 23, 2011)

X(72) = reflection of X(I) in X(J) for these (I,J): (1,960), (65,10), (3555,1)
X(72) = isogonal conjugate of X(28)
X(72) = isotomic conjugate of X(286)
X(72) = inverse-in-Fuhrmann circle of X(3419)
X(72) = anticomplement of X(942)
X(72) = X(I)-Ceva conjugate of X(J) for these (I,J): (8,10), (63,71), (69,306), (321,37)
X(72) = X(I)-cross conjugate of X(J) for these (I,J): (201,10), (228,37)
X(72) = crosspoint of X(I) and X(J) for these (I,J): (8,78), (63,69), (306,307)
X(72) = crosssum of X(I) and X(J) for these (I,J): (19,25), (34,56)
X(72) = crossdifference of any two points on line X(513)X(1430)
X(72) = X(I)-beth conjugate of X(J) for these (I,J): (8,65), (72,73), (78,72), (100,227), (644,72)


X(73)  CROSSPOINT OF INCENTER AND CIRCUMCENTER

Trilinears       sec B + sec C : sec C + sec A : sec A + sec B
Barycentrics  (cos B + cos C) sin 2A : (cos C + cos A) sin 2B : (cos A + cos B) sin 2C

X(73) = (r2 - 4R2 + s2)*X(1) - 6rR*X(2) + 4rR*X(3)    (Peter Moses, April 2, 2013)

X(73) lies on these lines:
1,4   3,212   6,41   21,651   35,74   36,54   37,836   42,65   55,64   57,386   66,976   68,1060   69,77   72,201   102,947   228,408   284,951   290,336   1036,1037   1057,1059

X(73) is the {X(1064),X(1066)}-harmonic conjugate of X(1). For a list of other harmonic conjugates of X(73), click Tables at the top of this page.

X(73) = isogonal conjugate of X(29)
X(73) = X(1)-Ceva conjugate of X(65)
X(73) = X(228)-cross conjugate of X(71)
X(73) = crosspoint of X(I) and X(J) for these (I,J): (1,3), (77,222), (226,307)
X(73) = crosssum of X(I) and X(J) for these (I,J): (1,4), (33,281)
X(73) = crossdifference of any two points on line X(243)X(522)
X(73) = X(I)-Hirst inverse of X(J) for these (I,J): (1,243), (65,851)
X(73) = X(I)-beth conjugate of X(J) for these (I,J): (1,1042), (3,73), (21,946), (72,72), (100,10), (101,73), (295,73)


X(74)  ISOGONAL CONJUGATE OF EULER INFINITY POINT

Trilinears       1/(cos A - 2 cos B cos C) : 1/(cos B - 2 cos C cos A) : 1/(cos C - 2 cos A cos B)
                     = 1/(3 cos A - 2 sin B sin C) : 1/(3 cos B - 2 sin C sin A) : 1/(3 cos C - 2 sin A sin B)
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a/[2a4 - (b2 - c2)2 - a2(b2 + c2)]

Barycentrics  a/(cos A - 2 cos B cos C) : b/(cos B - 2 cos C cos A) : c/(cos C - 2 cos A cos B)

X(74) = (r2 + 2rR + s2)*X(1) - R(6r + 9R)*X(2) + (r2 + 12rR + 18R2 - 3s2)*X(3)    (Peter Moses, April 2, 2013)

As the isogonal conjugate of the point in which the Euler line meets the line at infinity, X(74) lies on the circumcircle.

X(74) = circumcircle-antipode of X(110)
X(74) is the point of intersection, other than A, B, and C of the circumcircle and Jerabek hyperbola; also, X(74) is the antipode of X(4) on the Jerabek hyperbola. X(74) lies on the Darboux septic curve.

Let T be the triangle fromed by reflecting the orthic axis in the sidelines of ABC; then T is perspective to ABC, and the perspector ix X(74). Let A' be the point of intersection of the orthic axis and line BC, and define B' and C' cyclically. Let OA be the circumcenter of AB'C', and define Let OB and OC cyclically; then the lines AOA, BOB, COC concur in X(74). (Randy Hutson, August 26, 2014)

Let A'B'C' be the anticomplementary triangle. Let L be the line through A' parallel to the Euler line, and define B' and C' cyclically. Let L' be the reflection of L in sideline BC, and define B' and N' cyclically. The lines L', M', N' concur in X(74). (Randy Hutson, August 26, 2014)

Let A'B'C' be the X(3)-Fuhrmann triangle. Let A'' be the reflection of A in line B'C', and define B'' and C'' cyclically. Then A''B''C'' is inversely similar to ABC, with similitude center X(265), and A''B''C'' is perspective to ABC at X(74), which is also the orthocenter of A''B''C''. (Randy Hutson, August 26, 2014)

In Hyacinthos 8129 (10/4/03), Floor van Lamoen noted that if X(74) is denoted by J, then each of the points A,B,C,J is J of the other three, in analogy with the well known property of orthocentric systems (that is, each of the points A,B,C,H is the orthocenter of the other three).

X(74) lies on the Neuberg cubic and these lines:
1,3464   2,113   3,110   4,107   6,112   20,68   24,64   30,265   35,73   54,185   65,108   67,935   69,99   71,101   72,100   98,690   187,248   477,523   484,3465   511,691   512,842   550,930   1157,3484

X(74) = midpoint of X(20) and X(3448)
X(74) = reflection of X(I) in X(J) for these (I,J): (4,125), (110,3), (146,113), (399,1511)
X(74) = isogonal conjugate of X(30)
X(74) = isotomic conjugate of X(3260)
X(74) = complement of X(146)
X(74) = anticomplement of X(113)
X(74) = cevapoint of X(I) and X(J) for these (I,J): (15,16), (50,184)
X(74) = crosssum of X(I) and X(J) for these (I,J): (3,399), (616),617)
X(74) = X(I)-cross conjugate of X(J) for these (I,J): (186,54), (526,110)
X(74) = trilinear pole of line X(6)X(647)
X(74) = Ψ(X(6),X(647))
X(74) = reflection of X(477) in the Euler line
X(74) = reflection of X(842) in the Brocard axis
X(74) = reflection of X(2687) in the line X(1)X(3)
X(74) = relfection of X(1296) in the line X(3)X(351)
X(74) = {X(3),X(399)}-harmonic conjugate of X(1511)
X(74) = X(128)-of-excentral-triangle
X(74) = X(137)-of-hexyl-triangle
X(74) = X(1296)-of-circumsymmedial
X(74) = inverse-in-polar-circle of X(133)


X(75)  ISOTOMIC CONJUGATE OF INCENTER

Trilinears       1/a2 : 1/b2 : 1/c2
                        = 1/(1 - cos 2A) : 1/(1 - cos 2B) : 1/(1 - cos 2C)
                        = SA + S2 : SB + S2 : SC + S2

Barycentrics  1/a : 1/b : 1/c
Barycentrics  csc A : csc B : csc C

This is the center X(37) of the anticomplementary triangle.

X(75) lies on these lines:
1,86   2,37   6,239   7,8   9,190   10,76   19,27   21,272   31,82   32,746   38,310   42,1218   43,872   47,2216   48,336   72,1246   77,664   81,2214   87,3226   99,261   100,675   101,767   141,334   142,2321   144,391   149,2805   150,2893   158,240   183,1376   194,1107   219,1944   222,1943   225,264   234,556   244,1978   255,2190   257,698   269,1222   279,1219   280,309   298,1081   299,554   325,2886   491,1659   522,3261   523,876   537,668   538,1573   560,1580   689,745   700,971   728,1223   753,789   757,1468   758,994   775,1496   799,897   811,1099   901,2863   927,2751   934,2370940,1999   958,1975   982,1920   1089,1268   1150,3218&bsp;  1237,1240   1332,2989   1370,3434   1444,2217   1581,1934   1812,2219   1897,2000   1928,2085   1953,1959   2167,2168   2894,2897

X(75) is the {X(7),X(8)}-harmonic conjugate of X(69). For a list of other harmonic conjugates of X(75), click Tables at the top of this page.

X(75) = reflection of X(I) in X(J) for these (I,J): (192,37), (335,1086), (984,10)
X(75) = isogonal conjugate of X(31)
X(75) = isotomic conjugate of X(1)
X(75) = complement of X(192)
X(75) = anticomplement of X(37)
X(75) = anticomplementary conjugate of X(2895)
X(75) = X(I)-Ceva conjugate of X(J) for these (I,J): (76,312), (274,2), (310,76), (314,69)
X(75) = cevapoint of X(I) and X(J) for these (I,J): (1,63), (2,8), (7,347), (10,321), (244,514)

X(75) = X(I)-cross conjugate of X(J) for these (I,J):
(1,92), (2,85), (7,309), (8,312), (10,2), (38,1), (63,304), (244,514), (307,69), (321,76), (347,322), (522,190)

X(75) = crosspoint of X(I) and X(J) for these (I,J): (2,330), (274,310)
X(75) = crossdifference of any two points on line X(667)X(788)
X(75) = X(I)-Hirst inverse of X(J) for these (I,J): (2,350), (334,335)
X(75) = X(83)-aleph conjugate of X(31)

X(75) = X(I)-beth conjugate of X(J) for these (I,J):
(8,984), (75,7), (99,77), (314,75), (522,876), (645,9), (646,75), (668,75), (811,342)


X(76) = 3rd BROCARD POINT

Trilinears       1/a3 : 1/b3 : 1/c3
                        = csc(A - ω) : csc(B - ω) : csc(C - ω)

Barycentrics  1/a2 : 1/b2 : 1/c2

X(76) lies on these lines:
1,350   2,39   3,98   4,69   5,262   6,83   7,1240   8,668   10,75   13,299   14,298   17,303   18,302   20,3424   22,1799   25,1241   31,734   32,384   37,1218   85,226   95,96   100,767   107,2366   110,2367   115,626   141,698   148,2896   182,3406   187,3552   192,1221   251,1239   257,1926   275,276   297,343   321,561   330,1015   331,1231   333,1751   334,1089   335,871   338,599  485,491   486,492   524,598   620,1569   689,755   691,2868   693,764   761,789   799,1150   826,882   940,1509   1003,3053   1007,3090   1131,1271   1132,1270   1229,1446   1423,3403   1501,3115   1670,1677   1671,1676   1698,3097   2001,2909   2319,3500   2394,3267   3224,3225   3492,3506   3496,3512   3497,3509

X(76) is the {X(2),X(194)}-harmonic conjugate of X(39). For a list of other harmonic conjugates of X(76), click Tables at the top of this page.

X(76) = reflection of X(194) in X(39)
X(76) = isogonal conjugate of X(32)
X(76) = isotomic conjugate of X(6)
X(76) = complement of X(194)
X(76) = anticomplement of X(39)
X(76) = anticomplementary conjugate of X(2896)
X(76) = X(I)-Ceva conjugate of X(J) for these (I,J): (308,2), (310,75)
X(76) = cevapoint of X(I) and X(J) for these (I,J): (2,69), (6,22), (75,312), (311,343), (313,321), (339,525)
X(76) = X(I)-cross conjugate of X(J) for these (I,J): (2,264), (69,305), (141,2), (321,75), (343,69), (525,99)
X(76) = crosssum of X(669) and X(1084)
X(76) = crossdifference of any two points on line X(669)X(688)
X(76) = X(I)-beth conjugate of X(J) for these (I,J): (76,85), (799,348)


X(77) = ISOGONAL CONJUGATE OF X(33)

Trilinears       1/(1 + sec A) : 1/(1 + sec B) : 1/(1 + sec C)
                        = cos A sec2(A/2) : cos B sec2(B/2) : cos C sec2(C/2)
                        = (b2 + c2 - a2)/(b + c - a) : (c2 + a2 - b2)/(c + a - b) : (a2 + b2 - c2)/(a + b - c)
                        = SA(SA - bc) : SB(SB - ca) : SC(SC - ab)

Barycentrics  a/(1 + sec A) : b/(1 + sec B) : c/(1 + sec C)

X(77) lies on these lines:
1,7   2,189   6,241   9,651   29,34   40,947   55,1037   56,1036   57,81   63,219   65,969   69,73   75,664   102,934   283,603   309,318   738,951   988,1106   999,1057

X(77) = isogonal conjugate of X(33)
X(77) = isotomic conjugate of X(318)
X(77) = X(I)-Ceva conjugate of X(J) for these (I,J): (85,57), (86,7), (348,63)
X(77) = cevapoint of X(I) and X(J) for these (I,J): (1,223), (3,222)
X(77) = X(I)-cross conjugate of X(J) for these (I,J): (3,63), (73,222)

X(77) = X(I)-beth conjugate of X(J) for these (I,J):
(21,990), (69,69), (86,269), (99,75), (332,326), (336,77), (662,77), (664,77), (811,77)


X(78) = ISOGONAL CONJUGATE OF X(34)

Trilinears       1/(1 - sec A) : 1/(1 - sec B) : 1/(1 - sec C)
                        = cos A csc2(A/2) : cos B csc2(B/2) : cos C csc2(C/2)
                        = (b + c - a)(b2 + c2 - a2) : (c + a - b)(c2 + a2 - b2) : (a + b - c)(a2 + b2 - c2)
                        = SA(SA + bc) : SB(SB + ca) : SC(SC + ab)

Barycentrics  a/(1 - sec A) : b/(1 - sec B) : c/(1 - sec C)

If you have The Geometer's Sketchpad, you can view X(78).

X(78) lies on these lines:
1,2   3,63   4,908   9,21   20,329   29,33   37,965   38,988   40,100   46,758   55,960   56,480   57,404   69,73   101,205   207,653   210,958   212,283   220,949   226,377   271,394   273,322   280,282   345,1040   392,1057   474,942   517,945   644,728   999,1059

X(78) = isogonal conjugate of X(34)
X(78) = isotomic conjugate of X(273)
X(78) = X(I)-Ceva conjugate of X(J) for these (I,J): (69,63), (312,9), (332,345)
X(78) = X(I)-cross conjugate of X(J) for these (I,J): (3,271), (72,8), (212,9), (219,63)
X(78) = crosspoint of X(69) and X(345)
X(78) = crosssum of X(I) and X(J) for these (I,J): (25,608), (56,1406), (604,1395), (1042,1426)
X(78) = X(I)-beth conjugate of X(J) for these (I,J): (78,3), (643,40), (1043,1)


X(79) = ISOGONAL CONJUGATE OF X(35)

Trilinears       1/(1 + 2 cos A) : 1/(1 + 2 cos B) : 1/(1 + 2 cos C)
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc/(b2 + c2 - a2 + bc)
                        = g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A/2)(sin 3B/2)(sin 3C/2)

Barycentrics  h(a,b,c) : h(b,c,a) : h(c,a,b), where h(a,b,c) = 1/(b2 + c2 - a2 + bc)

X(79) = (2r + 3R)*X(1) + 6r*X(2) - 6r*X(3)    (Peter Moses, April 2, 2013)

Let A' be the reflection of X(1) in sideline BC, and define B' and C' cyclically. Then the lines AA', BB', CC' concur in X(79). (Eric Danneels, Hyacinthos 7892, 9/13/03)

X(79) lies on these lines:
1,30   8,758   9,46   12,484   21,36   33,1063   34,1061   35,226   57,90   65,80   104,946   314,320   388,1000

X(79) = reflection of X(191) in X(442)
X(79) = isogonal conjugate of X(35)
X(79) = isotomic conjugate of X(319)
X(79) = cevapoint of X(481) and X(482)
X(79) = crosssum of X(55) and X(1030)


X(80)  REFLECTION OF INCENTER IN FEUERBACH POINT

Trilinears       1/(1 - 2 cos A) : 1/(1 - 2 cos B) : 1/(1 - 2 cos C)
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc/(b2 + c2 - a2 - bc)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = 1/(b2 + c2 - a2 - bc)

X(80) = (2r + R)*X(1) - 6r*X(2) + 2r*X(3)    (Peter Moses, April 2, 2013)

X(80) lies on these lines:
1,5   2,214   7,150   8,149   9,528   10,21   30,484   33,1061   34,1063   36,104   40,90   46,84   65,79   313,314   497,1000   499,944   516,655   519,908   943,950

X(80) = midpoint of X(8) and X(149)
X(80) = reflection of X(I) in X(J) for these (I,J): (1,11), (100,10), (1317,1387)
X(80) = isogonal conjugate of X(36)
X(80) = isotomic conjugate of X(320)
X(80) = inverse-in-incircle of X(1387)
X(80) = inverse-in-Fuhrmann-circle of X(1)
X(80) = anticomplement of X(214)
X(80) = cevapoint of X(10) and X(519)
X(80) = X(I)-cross conjugate of X(J) for these (I,J): (44,2), (517,1)
X(80) = X(8)-beth conjugate of X(100)


X(81)  CEVAPOINT OF INCENTER AND SYMMEDIAN POINT

Trilinears       1/(b + c) : 1/(c + a) : 1/(a + b)
Barycentrics  a/(b + c) : b/(c + a) : c/(a + b)

X(81) = (r2 + 2rR + s2)*X(1) - 3rR*X(2) - 2r2*X(3)    (Peter Moses, April 2, 2013)

Let A'B'C' be the cevian triangle of X(1). Let A" be the symmedian point of triangle AB'C', and define B" and C" cyclically. Then the lines AA", BB", CC" concur in X(81). (Eric Danneels, Hyacinthos 7892, 9/13/03)

Let A'B'C' be the incentral triangle. Let LA be the reflection of B'C' in the internal angle bisector of vertex angle A, and define LB and LC cyclically. Let A'' = LB∩LC, B'' = LC∩LA, C'' = LA∩LB. The lines AA'', BB'', CC'' concur in X(81). (Randy Hutson, 9/23/2011)

If you have The Geometer's Sketchpad, you can view X(81).

X(81) lies on these lines:
1,21   2,6   7,27   8,1010   19,969   28,60   29,189   32,980   42,100   43,750   55,1002   56,959   57,77   65,961   88,662   99,739   105,110   145,1043   226,651   239,274   314,321   377,387   386,404   411,581   593,757   715,932   859,957   941,967   982,985   1019,1022   1051,1054   1098,1104

X(81) = isogonal conjugate of X(37)
X(81) = isotomic conjugate of X(321)
X(81) = anticomplement of X(1211)
X(81) = X(I)-Ceva conjugate of X(J) for these (I,J): (7,229), (86,21), (286,28)
X(81) = cevapoint of X(I) and X(J) for these (I,J): (1,6), (57,222), (58,284)
X(81) = X(I)-cross conjugate of X(J) for these (I,J): (1,86), (3,272), (6,58), (57,27), (284,21)
X(81) = crosspoint of X(274) and X(286)
X(81) = crosssum of X(I) and X(J) for these (I,J): (1,846), (6,1030), (42,1334), (213,228)
X(81) = crossdifference of any two points on line X(512)X(661)
X(81) = X(I)-beth conjugate of X(J) for these (I,J): (333,333), (643,81), (645,81), (648,81), (662,81), (931,81)


X(82) = ISOGONAL CONJUGATE OF X(38)

Trilinears       1/(b2 + c2) : 1/(c2 + a2) : 1/(a2 + b2)
                        = sin A csc(A + ω) : sin B csc(B + ω) : sin C csc(C + ω)

Barycentrics  a/(b2 + c2) : b/(c2 + a2) : c/(a2 + b2)

X(82) lies on these lines: 1,560   10,83   31,75   37,251   58,596   689,715   759,827

X(82) = isogonal conjugate of X(38)
X(82) = isotomic conjugate of X(1930)
X(82) = cevapoint of X(1) and X(31)


X(83)  CEVAPOINT OF CENTROID AND SYMMEDIAN POINT

Trilinears       bc/(b2 + c2) : ca/(c2 + a2) : ab/(a2 + b2)
                        = csc(A + ω) : csc(B + ω) : csc(C + ω)

Barycentrics  1/(b2 + c2) : 1/(c2 + a2) : 1/(a2 + b2)

Let K denote the symmedian point, X(6). Let A'B'C' be the cevian triangle of K. Let KA be K of the triangle AB'C'; let KB be K of A'BC' and let KC be K of A'B'C. The lines AKA, BKB, CKC concur in X(83). (Randy Hutson, 9/23/2011)

X(83) lies on these lines:
2,32   3,262   4,182   5,98   6,76   10,82   17,624   18,623   39,99   213,239   217,287   275,297   597,671   689,729

X(83) = isogonal conjugate of X(39)
X(83) = isotomic conjugate of X(141)
X(83) = complement of X(2896)
X(83) = cevapoint of X(2) and X(6)
X(83) = X(I)-cross conjugate of X(J) for these (I,J): (2,308), (6,251), (512,99)


X(84) = ISOGONAL CONJUGATE OF X(40)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/(cos B + cos C - cos A - 1)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(84) = (r + 2R)*X(1) - 6R*X(2) + (4R - 2r)*X(3)    (Peter Moses, April 2, 2013)

Let A',B',C' be the excenters. The perpendiculars from B' to AB and from C' to AC meet in a point A". Points B" and C" are determined cyclically. The hexyl triangle, A"B"C", is perspective to ABC, and X(84) is the perspector. Also, X(84) is X(68)-of-the-hexyl-triangle.

X(84) lies on the Darboux cubic and these lines: 1,221   3,9   4,57   7,946   8,20   21,285   33,603   36,90   46,80   58,990   64,3353   171,989   256,988   294,580   309,314   581,941   944,1000   2130,3345   3346,3472   3347,3355

X(84) = reflection of X(I) in X(J) for these (I,J): (40,1158), (1490,3)
X(84) = isogonal conjugate of X(40)
X(84) = isotomic conjugate of X(322)
X(84) = X(I)-Ceva conjugate of X(J) for these (I,J): (189,282), (280,1)
X(84) = X(I)-cross conjugate of X(J) for these (I,J): (19,57), (56,1)
X(84) = X(280)-aleph conjugate of X(84)
X(84) = X(I)-beth conjugate of X(J) for these (I,J): (271,3), (280,280), (285,84)


X(85)  ISOTOMIC CONJUGATE OF X(9)

Trilinears       b2c2/(b + c - a) : c2a2/(c + a - b) : a2b2/(a + b - c)
                        = tan(A/2) csc2A : tan(B/2) csc2B : tan(C/2) csc2C

Barycentrics  bc/(b + c - a) : ca/(c + a - b) : ab/(a + b - c)

X(85) lies on these lines:
1,664   2,241   7,8   12,120   29,34   56,870   57,274   76,226   92,331   109,767   150,355   264,309

X(85) = isogonal conjugate of X(41)
X(85) = isotomic conjugate of X(9)
X(85) = complement of X(3177)
X(85) = anticomplement of X(1212)
X(85) = X(274)-Ceva conjugate of X(348)
X(85) = cevapoint of X(I) and X(J) for these (I,J): (1,169), (2,7), (57,77), (92,342)
X(85) = X(I)-cross conjugate of X(J) for these (I,J): (2,75), (57,273), (92,309), (142,2), (226,7)

X(85) = X(I)-beth conjugate of X(J) for these (I,J):
(76,76), (85,279), (99,1), (274,85), (668,85), (789,85), (799,85), (811,85)


X(86)   CEVAPOINT OF INCENTER AND CENTROID

Trilinears       bc/(b + c) : ca/(c + a) : ab/(a + b)
Barycentrics  1/(b + c) : 1/(c + a) : 1/(a + b)

X(86) = 2(r2 + 2rR + s2)*X(1) + 3(r2 + s2)*X(2) - 4r2*X(3)    (Peter Moses, April 2, 2013)

X(86) lies on these lines:
1,75   2,6   7,21   10,319   29,34   37,190   58,238   60,272   99,106   110,675   142,284   239,1100   269,1088   283,307   310,350   741,789   870,871

X(86) = isogonal conjugate of X(42)
X(86) = isotomic conjugate of X(10)
X(86) = complement of X(1654)
X(86) = anticomplement of X(1213)
X(86) = X(274)-Ceva conjugate of X(333)
X(86) = cevapoint of X(I) and X(J) for these (I,J): (1,2), (7,77), (21,81)
X(86) = crosssum of X(1) and X(1045)
X(86) = crossdifference of any two points on line X(512)X(798)
X(86) = X(I)-cross conjugate of X(J) for these (I,J): (1,81), (2,274), (7,286), (21,333), (58,27), (513,190)
X(86) = X(I)-beth conjugate of X(J) for these (I,J): (86,1014), (99,86), (261,86), (314,314), (645,86), (811,86)


X(87)   X(2)-CROSS CONJUGATE OF X(1)

Trilinears       1/(ab + ac - bc) : 1/(bc + ba - ca) : 1/(ca + cb - ab)
Barycentrics  a/(ab + ac - bc) : b/(bc + ba - ca) : c/(ca + cb - ab)

X(87) lies on these lines: 1,192   6,43   9,292   10,979   34,242   56,238   58,978   106,932

X(87) = isogonal conjugate of X(43)
X(87) = cevapoint of X(2) and X(330)
X(87) = X(2)-cross conjugate of X(1)
X(87) = X(932)-beth conjugate of X(87)


X(88) = ISOGONAL CONJUGATE OF X(44)

Trilinears       1/(b + c - 2a) : 1/(c + a - 2b) : 1/(a + b - 2c)
Barycentrics  a/(b + c - 2a) : b/(c + a - 2b) : c/(a + b - 2c)

X(88) = (3r2 + 6rR - s2)*X(1) + 9rR*X(2) - 6r2*X(3)    (Peter Moses, April 2, 2013)

X(88) lies on these lines: 1,100   2,45   6,89   28,162   44,679   57,651   81,662   105,901   274,799   278,653   279,658   291,660

X(88) = isogonal conjugate of X(44)
X(88) = cevapoint of X(I) and X(J) for these (I,J): (1,44), (6,36)
X(88) = X(I)-cross conjugate of X(J) for these (I,J): (44,1), (517,7)
X(88) = X(I)-aleph conjugate of X(J) for these (I,J): (88,1), (679,88), (903,63), (1022,1052)
X(88) = X(333)-beth conjugate of X(190)


X(89) = ISOGONAL CONJUGATE OF X(45)

Trilinears       1/(2b + 2c - a) : 1/(2c + 2a - b) : 1/(2a + 2b - c)
Barycentrics  a/(2b + 2c - a) : b/(2c + 2a - b) : c/(2a + 2b - c)

X(89) lies on these lines: 1,902   2,44   6,88   649,1022

X(89) = isogonal conjugate of X(45)


X(90) = X(3)-CROSS CONJUGATE OF X(1)

Trilinears       1/(cos B + cos C - cos A) : 1/(cos C + cos A - cos B) : 1/(cos A + cos B - cos C)
Barycentrics  a/(cos B + cos C - cos A) : b/(cos C + cos A - cos B) : c/(cos A + cos B - cos C)

X(90) = (r + R)2*X(1) - 6rR*X(2) - 2r(r - R)*X(3)    (Peter Moses, April 2, 2013)

X(90) lies on these lines: 1,155   4,46   9,35   21,224   33,47   36,84   40,80   57,79

X(90) = isogonal conjugate of X(46)
X(90) = X(3)-cross conjugate of X(1)


X(91) = ISOGONAL CONJUGATE OF X(47)

Trilinears       sec 2A : sec 2B : sec 2C
Barycentrics  sin A sec 2A : sin B sec 2B : sin C sec 2C

X(91) lies on these lines: 19,920   31,1087   37,498   47,92   63,921   65,68   225,847   255,1109   759,925

X(91) = isogonal conjugate of X(47)
X(91) = X(48)-cross conjugate of X(92)
X(91) = trilinear product of X(485) and X(486)


X(92)  CEVAPOINT OF INCENTER AND CLAWSON POINT

Trilinears       csc 2A : csc 2B : csc 2C
Barycentrics  sec A : sec B : sec C
X(92) = X(4) - ((r + 2R)2 - s2)*X(8)

Let LA be the line through X(4) parallel to the internal bisector of angle A, and let
A' = BC∩LA. Define B' and C' cyclically.

Alexei Myakishev, "The M-Configuration of a Triangle," Forum Geometricorum 3 (2003) 135-144,

proves that the lines AA', BB', CC' concur in X(92). He notes that another construction follows from Proposition 2 of the article: let A1 be the midpoint of the arc BC of the circumcircle that passes through A, and let A2 be the point, other than A, in which the A-altitude meets the circumcircle. Let A" = A1A2∩BC. Define B" and C" cyclically. Then the lines AA", BB", CC" concur in X(92).

X(92) lies on these lines:
1,29   2,273   4,8   7,189   10,1838   19,27   25,242   28,2975   31,162   33,1897   34,1220   38,240   40,412   47,91   48,2167   53,4415   55,243   56,1940   57,653   81,2995   85,331   100,917   108,1311   171,1430   226,342   239,607   255,1087   257,297   264,306   304,561   345,3262   388,1118   394,1943   406,1068   427,2969   429,3948   429,3948   459,1446   497,1857   518,1859   608,894   651,2988   823,2349   938,3176   942,1148   960,1882   984,1860   994,1845   1146,1952   1172,2997   1211,1865   1309,2717   1435,3306   1585,1659   1621,4183   1707,1733   1726,1746   1731,1751   1785,4656   1842,1891   1844,3874   1870,5136   1947,2994   1954,1955   1956,2632   1973,3112   2064,3596      2331,5256   2399,4391   3064,4468   4198,4968

X(92) = isogonal conjugate of X(48)
X(92) = isotomic conjugate of X(63)
X(92) = anticomplement of X(1214)
X(92) = anticomplementary conjugate of X(2897)
X(92) = X(I)-Ceva conjugate of X(J) for these (I,J): (85, 342), (264,318), (286,4), (331,273)
X(92) = cevapoint of X(I) and X(J) for these (I,J): (1,19), (4,281), (47,48), (196,278)
X(92) = X(I)-cross conjugate of X(J) for these (I,J): (1,75), (4,273), (19,158), (48,91), (226,2), (281,318)
X(92) = crosspoint of X(I) and X(J) for these (I,J): (85,309), (264,331)
X(92) = crossdifference of every pair of points on line X(810)X(822)
X(92) = X(275)-aleph conjugate of X(47)
X(92) = X(I)-beth conjugate of X(J) for these (I,J): (92,278), (312,329), (648,57)


X(93) = ISOGONAL CONJUGATE OF X(49)

Trilinears       sec 3A : sec 3B : sec 3C
Barycentrics  sin A sec 3A : sin B sec 3B : sin C sec 3C

X(93) lies on these lines: 4,562   49,94   186,252

X(93) = isogonal conjugate of X(49)
X(93) = X(50)-cross conjugate of X(94)


X(94) = ISOGONAL CONJUGATE OF X(50)

Trilinears       csc 3A : csc 3B : csc 3C
Barycentrics  sin A csc 3A : sin B csc 3B : sin C csc 3C

X(94) lies on these lines: 2,300   4,143   23,98   49,93   96,925   275,324

X(94) = isogonal conjugate of X(50)
X(94) = isotomic conjugate of X(323)
X(94) = cevapoint of X(49) and X(50)
X(94) = X(I)-cross conjugate of X(J) for these (I,J): (30,264), (50,93), (265,328)
X(94) = X(300)-Hirst inverse of X(301)


X(95)  CEVAPOINT OF CENTROID AND CIRCUMCENTER

Trilinears       b2c2 sec(B - C) : c2a2 sec(C - A) : a2b2 sec(A - B)
Barycentrics  bc sec(B - C) : ca sec(C - A) : ab sec(A - B)

X(95) lies on these lines:
2,97   3,264   54,69   76,96   99,311   140,340   141,287   160,327   183,305   216,648   307,320

X(95) = isogonal conjugate of X(51)
X(95) = isotomic conjugate of X(5)
X(95) = anticomplement of X(233)
X(95) = X(276)-Ceva conjugate of X(275)
X(95) = cevapoint of X(I) and X(J) for these (I,J): (2,3), (6,160), (54,97)
X(95) = X(I)-cross conjugate of X(J) for these (I,J): (2,276), (3,97), (54,275), (140,2), (340,1494)


X(96) = ISOGONAL CONJUGATE OF X(52)

Trilinears       sec 2A sec(B - C) : sec 2B sec(C - A) : sec 2C sec(A - B)
Barycentrics  a sec 2A sec(B - C) : b sec 2B sec(C - A) : c sec 2C sec(A - B)

X(96) lies on these lines: 2,54   4,231   24,847   76,95   94,925

X(96) = isogonal conjugate of X(52)
X(96) = cevapoint of X(3) and X(68)
X(96) = X(3)-cross conjugate of X(54)


X(97) = ISOGONAL CONJUGATE OF X(53)

Trilinears       cot A sec(B - C) : cot B sec(C - A) : cot C sec(A - B)
Barycentrics  cos A sec(B - C) : cos B sec(C - A) : cos C sec(A - B)

X(97) lies on these lines: 2,95   3,54   110,418   216,288   276,401

X(97) = isogonal conjugate of X(53)
X(97) = isotomic conjugate of X(324)
X(97) = X(95)-Ceva conjugate of X(54)
X(97) = X(3)-cross conjugate of X(95)



leftri Centers 74, 98 - 112, rightri
and others lie on the circumcircle. Mappings Λ and Ψ derived from such a point P for application to points X, are defined here:

Λ(P,X) = isogonal conjugate of the point where line PX meets the line at infinity.

Let Y = Λ(P,X), let Q = isogonal conjugate of P, and let Y and Z be the points where line YQ meets the circumcircle;
then Ψ(P,X) = Z.
underbar


X(98) = TARRY POINT

Trilinears       sec(A + ω) : sec(B + ω) : sec(C + ω)
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc/(b4 + c4 - a2b2 - a2c2)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = 1/(b4 + c4 - a2b2 - a2c2)

X(98) = 2(r2 + 4rR - s2)(r2 + 2rR + s2)*X(1) + 3(r4 + 4Rr3 + 2r2s2 - 4rRs2 + s4)*X(2) - 2(r2 + 4rR - s2)(3r2 + 4rR - s2)    (Peter Moses, April 2, 2013)

If you have The Geometer's Sketchpad, you can view X(98).

X(98) = circumcircle-antipode of X(99)
X(98) = the point of intersection, other than A, B, and C, of the circumcircle and Kiepert hyperbola.
X(98) = Ψ(X(101), X(100)

J. W. Clawson, "Points on the circumcircle," American Mathematical Monthly 32 (1925) 169-174.

X(98) lies on these lines:
2,110   3,76   4,32   5,83   6,262   10,101   13,1080   14,383   20,148   22,925   23,94   25,107   30,671   100,228   109,171   186,935   275,427   376,543   381,598   385,511   468,685   523,842   620,631   804,878

X(98) is the {X(2),X(147)}-harmonic conjugate of X(114). For a list of harmonic conjugates, click Tables at the top of this page.

X(98) = midpoint between X(20) and X(148)
X(98) = reflection of X(I) in X(J) for these (I,J): (4,115), (99,3), (147,114), (1513,230)
X(98) = isogonal conjugate of X(511)
X(98) = isotomic conjugate of X(325)
X(98) = complement of X(147)
X(98) = anticomplement of X(114)
X(98) = X(290)-Ceva conjugate of X(287)
X(98) = cevapoint of X(I) and X(J) for these (I,J): (2,385), (6,237)
X(98) = X(I)-cross conjugate of X(J) for these (I,J): (230,2), (237,6), (248,287), (446,511)
X(98) = crosssum of X(385) and X(401)
X(98) = X(2)-Hirst inverse of X(287)


X(99) = STEINER POINT

Trilinears       bc/(b2 - c2) : ca/(c2 - a2) : ab/(a2 - b2)
                        = b2c2 csc(B - C) : c2a2 csc(C - A) : a2b2 csc(A - B)

Barycentrics  1/(b2 - c2) : 1/(c2 - a2) : 1/(a2 - b2)

B>X(99) = 2(r2 + 4rR - s2)(r2 + 2rR + s2)*X(1) - 3(r4 + 4Rr3 + 2r2s2 - 4rRs2 + s4)*X(2) - 4r2(r2 + 4rR + 5s2)*X(3)    (Peter Moses, April 2, 2013)

X(99) = circumcircle-antipode of X(98)
X(99) = the point of intersection, other than A, B, and C, of the circumcircle and Steiner ellipse. X(99) = Ψ(X(6), X(2))

Let LA be the reflection of the line X(3)X(6) in line BC, and define LB and LC cyclically. Let A' = LB∩LC, B' = LC∩LA, C' = LA∩LB. The lines AA', BB', CC' concur in X(99). (Randy Hutson, 9/23/2011)

X(99) is the only point on the circumcircle whose isotomic conjugate lies on the line at infinity. (Randy Hutson, 9/23/2011)

If you have The Geometer's Sketchpad, you can view the following dynamic sketches:
X(99) and Steiner Circum-ellipse (showing X(99) and an area-ratio property)

For more information on the Steiner circum-ellipse, visit MathWorld.

X(99) lies on these lines:
1,741   2,111   3,76   4,114   6,729   13,303   14,302   20,147   21,105   22,305   30,316   31,715   32,194   36,350   38,745   39,83   58,727   69,74   75,261   81,739   86,106   95,311   100,668   101,190   102,332   103,1043   104,314   108,811   109,643   110,690   112,648   141,755   163,825   187,385   249,525   264,378   286,915   298,531   299,530   310,675   476,850   512,805   523,691   524,843   666,919   669,886   670,804   692,785   695,711   813,1016   889,898

X(99) is the {X(39),X(384)}-harmonic conjugate of X(83). For a list of other harmonic conjugates of X(99), click Tables at the top of this page.

X(99) = midpoint of X(I) and X(J) for these (I,J): (20,147), (616,617)
X(99) = reflection of X(I) in X(J) for these (I,J): (4,114), (13,619), (14,618), (98,3), (115,620), (148,115), (316,325), (385,187), (671,2)

X(99) = isogonal conjugate of X(512)
X(99) = isotomic conjugate of X(523)
X(99) = complement of X(148)
X(99) = anticomplement of X(115)
X(99) = cevapoint of X(I) and X(J) for these (I,J): (2,523), (3,525), (39,512), (100,190)
X(99) = X(1019)-cross conjugate of X(1509)
X(99) = crossdifference of any two points on line X(351)X(865)
X(99) = X(I)-cross conjugate of X(J) for these (I,J): (3,249), (22,250), (512,83), (523,2), (525,76)
X(99) = X(21)-beth conjugate of X(741)


X(100)  ANTICOMPLEMENT OF FEUERBACH POINT

Trilinears       1/(b - c) : 1/(c - a) : 1/(a - b)
                        = (a - b)(a - c) : (b - c)(b - a) : (c - a)(c - b)

Barycentrics  a/(b - c) : b/(c - a) : c/(a - b)

X(100) = 2R*X(1) - 3R*X(2) + 2r*X(3)    (Peter Moses, April 2, 2013)

X(100) = circumcircle-antipode of X(104)
X(100) = Ψ(X(6), X(1))

X(100) lies on these lines:
1,88   2,11   3,8   4,119   6,739   7,1004   9,1005   10,21   20,153   22,197   31,43   32,713   36,519   37,111   40,78   42,81   46,224   56,145   59,521   63,103   72,74   75,675   76,767   92,917   98,228   99,668   101,644   107,823   108,653   109,651   110,643   112,162   144,480   190,659   198,346   213,729   238,899   281,1013   329,972   442,943   484,758   513,765   516,908   517,953   518,840   522,655   560,697   594,1030   645,931   649,660   650,919   658,664   667,898   693,927   731,869   733,893   753,984   756,846   789,874   976,986

X(100) is the {X(10),X(35)}-harmonic conjugate of X(21). For a list of other harmonic conjugates of X(100), click Tables at the top of this page.

X(100) = X(113)-of-the-hexyl-triangle.

Let LA be the reflection of the line X(1)X(3) in line BC, and define LB and LC cyclically. Let A' = LB∩LC, B' = LC∩LA, C' = LA∩LB. The lines AA', BB', CC' concur in X(100). (Randy Hutson, 9/23/2011)

X(100) = midpoint of X(20) and X(153)
X(100) = reflection of X(I) in X(J) for these (I,J): (1,214), (4,119), (8,1145), (80,10), (104,3), (145,1317), (149,11), (962,1537), (1156,9), (1320,1), (1484,140)

X(100) = isogonal conjugate of X(513)
X(100) = isotomic conjugate of X(693)
X(100) = complement of X(149)
X(100) = anticomplement of X(11)
X(100) = X(99)-Ceva conjugate of X(190)
X(100) = cevapoint of X(I) and X(J) for these (I,J): (1,513), (3,521), (10,522), (142,514), (442,523)
X(100) = X(I)-cross conjugate of X(J) for these (I,J): (3,59), (513,1), (521,8), (522,21)
X(100) = crosssum of X(I) and X(J) for these (I,J): (1,1054), (244,764), (512,661), (649,663)
X(100) = crossdifference of every pair of points on line X(244)X(665)
X(100) = X(1)-line conjugate of X(244)

X(100) = X(I)-aleph conjugate of X(J) for these (I,J):
(1,1052), (100,1), (190,63), (643,411), (666,673), (765,100), (1016,190)

X(100) = X(I)-beth conjugate of X(J) for these (I,J):
(8,80), (21,106), (100,109), (333,673), (643,100), (765,100)


X(101) = Ψ(INCENTER, SYMMEDIAN POINT)

Trilinears       a/(b - c) : b/(c - a) : c/(a - b)
                        = a(a - b)(a - c) : b(b - c)(b - a) : c(c - a)(c - b)

Barycentrics  a2/(b - c) : b2/(c - a) : c2/(a - b)

B>X(101) = (r 2 + 6rR + 8R2 + s2)*X(1) - 6R(r + 4R)*X(2) - 2(r2 + 4rR - s2)*X(3)    (Peter Moses, April 2, 2013)

X(101) = circumcircle-antipode of X(103)
X(101) = Ψ(X(1), X(6))
X(101) = X(114)-of-the-hexyl-triangle

Let LA be the reflection of the line X(1)X(7) in line BC, and define LB and LC cyclically. Let A' = LB∩LC, B' = LC∩LA, C' = LA∩LB. The lines AA', BB', CC' concur in X(101). (Randy Hutson, 9/23/2011)

X(101) lies on these lines:
1,41   2,116   3,103   4,118   6,106   9,48   10,98   19,913   20,152   31,609   32,595   36,672   37,284   40,972   42,111   56,218   58,172   59,657   71,74   75,767   78,205   99,190   100,644   102,198   109,654   110,163   514,664   517,910   522,929   560,713   643,931   649,901   651,934   663,919   667,813   668,789   692,926   733,904   743,869   761,984   765,898

X(101) = midpoint of X(20) and X(152)
X(101) = reflection of X(I) in X(J) for these (I,J): (4,118), (103,3), (150,116)
X(101) = isogonal conjugate of X(514)
X(101) = isotomic conjugate of X(3261)
X(101) = complement of X(150)
X(101) = anticomplement of X(116)
X(101) = X(59)-Ceva conjugate of X(55)
X(101) = cevapoint of X(354) and X(513)
X(101) = X(I)-cross conjugate of X(J) for these (I,J): (55,59), (199,250)
X(101) = crosssum of X(I) and X(J) for these (I,J): (513,650), (523,661), (649,1459)
X(101) = crossdifference of every pair of points on line X(11)X(244)
X(101) = X(I)-aleph conjugate of X(J) for these (I,J): (100,165), (509,1052), (662,572), (664,169)
X(101) = X(I)-beth conjugate of X(J) for these (I,J): (21,105), (644,644)


X(102) = Λ(INCENTER, ORTHOCENTER)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/[sin B (sec A - sec B) + sin C (sec A - sec C)]
                        = g(a,b,c) : g(b,c,a) : g(c,a,b), where
                        g(a,b,c) = a/[2a5 + (b + c)a4 - 2(b2 + c2)a3 - (b + c)(b2 - c2)2]

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where
g(A,B,C) = (sin A)/[sin B (sec A - sec B) + sin C (sec A - sec C)]

X(102) = circumcircle-antipode of X(109)
X(102) = Λ(X(1), X(4))

X(102) lies on these lines:
1,108   2,117   3,109   4,124   19,282   29,107   40,78   73,947   77,934   99,332   101,198   103,928   110,283   112,284   226,1065   516,929

X(102) = midpoint of X(20) and X(153)
X(102) = reflection of X(I) in X(J) for these (I,J): (4,124), (109,3), (151,117)
X(102) = isogonal conjugate of X(515)
X(102) = complement of X(151)
X(102) = anticomplement of X(117)
X(102) = X(21)-beth conjugate of X(108)


X(103) = ANTIPODE OF X(101)

Trilinears       a/[(a - b) cot C + (a - c) cot B] : b/[(b - c) cot A + (b - a) cot C] : c/[(c - a) cot B + (c - b) cot A]
                        = 1/(a2 - b2cos C - c2 cos B) : 1/(b2 - c2cos A - a2 cos C) : 1/(c2 - a2cos B - c2 cos A)

Barycentrics  f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a2/[(a - b) cot C + (a - c) cot B]

X(103) = circumcircle-antipode of X(101)
X(103) = Ψ(X(101), X(3))
X(103) = X(115)-of-the-hexyl-triangle

X(103) lies on these lines:
1,934   2,118   3,101   4,116   20,150   27,107   33,57   55,109   58,112   63,100   99,1043   102,928   295,813   376,544   515,929   516,927   572,825   672,919   910,971

X(103) = midpoint of X(20) and X(150)
X(103) = reflection of X(I) in X(J) for these (I,J): (4,116), (101,3), (152,118)
X(103) = isogonal conjugate of X(516)
X(103) = complement of X(152)
X(103) = anticomplement of X(118)
X(103) = X(21)-beth conjugate of X(934)


X(104) = ANTIPODE OF X(100)

Trilinears       1/(-1 + cos B + cos C) : 1/(-1 + cos C + cos A) : 1/(-1 + cos C + cos B)
Barycentrics  a/(-1 + cos B + cos C) : b/(-1 + cos C + cos A) : c/(-1 + cos C + cos B)

X(104) = 2R*X(1) - 3R*X(2) + (2R - 2r)*X(3)    (Peter Moses, April 2, 2013)

X(104) = circumcircle-antipode of X(100)
X(104) is the point of intersection, other than A, B, and C, of the circumcircle and Feuerbach hyperbola
X(104) = Λ(X(1), X(3))
X(104) = Ψ(X(101), X(9))
X(104) = X(125)-of-the-hexyl-triangle

Let LA be the reflection of the line X(1)X(513) in line BC, and define LB and LC cyclically. Let A' = LB∩LC, B' = LC∩LA, C' = LA∩LB. The lines AA', BB', CC' concur in X(104). (Randy Hutson, 9/23/2011)

X(104) lies on these lines:
1,109   2,119   3,8   4,11   7,934   9,48   20,149   21,110   28,107   36,80   55,1000   79,946   99,314   105,885   112,1108   256,1064   294,919   355,404   376,528   513,953   517,901   631,958

X(104) = midpoint of X(20) and X(149)
X(104) = reflection of X(I) in X(J) for these (I,J): (4,11), (100,3), (153,119), (1537,1387)
X(104) = isogonal conjugate of X(517)
X(104) = isotomic conjugate of X(3262)
X(104) = complement of X(153)
X(104) = anticomplement of X(119)
X(104) = cevapoint of X(I) and X(J) for these (I,J): (1,36), (44,55)
X(104) = X(21)-beth conjugate of X(109)


X(105) = Λ(INCENTER, SYMMEDIAN POINT)

Trilinears       1/[b2 + c2 - a(b + c)] : 1/[c2 + a2 - b(c + a)] : 1/[a2 + b2 - c(a + b)]
Barycentrics  a/[b2 + c2 - a(b + c)] : b/[c2 + a2 - b(c + a)] : c/[a2 + b2 - c(a + b)]

X(105) = Λ(X(1), X(6))
X(105) = Ψ(X(101), X(1))

X(105) lies on these lines:
1,41   2,11   3,277   6,1002   21,99   25,108   28,112   31,57   56,279   81,110   88,901   104,885   106,1022   165,1054   238,291   330,932   513,840   644,1083   659,884   666,898   825,985   910,919   961,1104

X(105) = reflection of X(I) in X(J) for these (I,J): (644,1083), (1292,3)
X(105) = isogonal conjugate of X(518)
X(105) = anticomplement of X(120)
X(105) = cevapoint of X(1) and X(238)
X(105) = X(1)-Hirst inverse of X(294)
X(105) = X(I)-beth conjugate of X(J) for these (I,J): (21,101), (927,105)


X(106) = Λ(INCENTER, CENTROID)

Trilinears       a/(2a - b - c) : b/(2b - c - a) : c/(2c - a - b)
Barycentrics  a2/(2a - b - c) : b2/(2b - c - a) : c2/(2c - a - b)

X(106) = Λ(X(1), X(2))
X(106) = Ψ(X(101), X(6))
X(106) = X(122)-of-the-hexyl-triangle

X(106) lies on these lines:
1,88   2,121   6,101   34,108   36,901   56,109   58,110   86,99   87,932   105,1022   238,898   269,934   292,813   614,998   663,840   789,870   833,977   919,1055

X(106) = reflection of X(1293) in X(3)
X(106) = isogonal conjugate of X(519)
X(106) = isotomic conjugate of X(3264)
X(106) = anticomplement of X(121)
X(106) = X(36)-cross conjugate of X(58)
X(106) = X(I)-beth conjugate of X(J) for these (I,J): (21,100), (901,106)


X(107) = Ψ(SYMMEDIAN POINT, ORTHOCENTER)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/[cos A (sin 2B - sin 2C)]
                        = g(a,b,c) : g(b,c,a) : g(c,a,b) where g(a,b,c) = bc/[(b2 - c2)(b2 + c2 - a2)2]

Barycentrics  1/[(b2 - c2)(b2 + c2 - a2)2] : 1/[(c2 - a2)(c2 + a2 - b2)2] : 1/[(a2 - b2)(a2 + b2 - c2)2]

X(107) = Ψ(X(6), X(4))

X(107) lies on these lines:
2,122   4,74   24,1093   25,98   27,103   28,104   29,102   51,275   100,823   109,162   110,648   111,393   158,759   186,477   250,687   450,511   468,842   741,1096

X(107) = reflection of X(I) in X(J) for these (I,J): (4,133), (1294,3)
X(107) = isogonal conjugate of X(520)
X(107) = isotomic conjugate of X(3265)
X(107) = anticomplement of X(122)
X(107) = cevapoint of X(4) and X(523)
X(107) = X(I)-cross conjugate of X(J) for these (I,J): (24,250), (108,162), (523,4)
X(107) = trilinear pole of line X(4)X(6)


X(108) = Ψ(CIRCUMCENTER, INCENTER)

Trilinears       a/(sec B - sec C) : b/(sec C - sec A): c/(sec A - sec B)
                        = g(a,b,c) : g(b,c,a) : g(c,a,b) where g(a,b,c) = 1/[(b - c)(b + c - a)(b2 + c2 - a2)]

Barycentrics  a2/(sec B - sec C) : b2/(sec C - sec A): c2/(sec A - sec B)

X(108) = Ψ(X(3), X(1))
X(108) = Ψ(X(1), X(4))

X(108) lies on these lines:
1,102   2,123   4,11   7,1013   12,451   24,915   25,105   28,225   33,57   34,106   40,207   55,196   65,74   99,811   100,653   109,1020   110,162   204,223   273,675   318,404   331,767   388,406   429,961   608,739   648,931

X(108) = reflection of X(1295) in X(3)
X(108) = isogonal conjugate of X(521)
X(108) = anticomplement of X(123)
X(108) = X(162)-Ceva conjugate of X(109)
X(108) = cevapoint of X(I) and X(J) for these (I,J): (56,513), (429,523)
X(108) = X(513)-cross conjugate of X(4)
X(108) = crosspoint of X(107) and X(162)
X(108) = crosssum of X(520) and X(656)
X(108) = X(I)-beth conjugate of X(J) for these (I,J): (21,102), (162,108)


X(109) = Ψ(INCENTER, CIRCUMCENTER)

Trilinears       a/(cos B - cos C) : b/(cos C - cos A): c/(cos A - cos B)
                        = g(a,b,c) : g(b,c,a) : g(c,a,b) where g(a,b,c) = a/[(b - c)(b + c - a)]

Barycentrics  a2/(cos B - cos C) : b2/(cos C - cos A): c2/(cos A - cos B)

X(109) = circumcircle-antipode of X(102)
X(109) = Ψ(X(1), X(3))
X(109) = trilinear product X(1381)*X(1382)

If the line X(1)X(4) is reflected in every side of triangle ABC, then the reflections concur in X(109). (Randy Hutson, 9/23/2011)

X(109) lies on these lines:
1,104   2,124   3,102   4,117   7,675   20,151   31,57   34,46   35,73   36,953   40,255   55,103   56,106   58,65   59,901   85,767   98,171   99,643   100,651   101,654   107,162   108,1020   112,163   165,212   191,201   278,917   284,296   478,573   579,608   604,739   649,919   658,927   662,931   840,902

X(109) = midpoint of X(20) and X(151)
X(109) = reflection of X(I) in X(J) for these (I,J): (4,117), (102,3)
X(109) = isogonal conjugate of X(522)
X(109) = anticomplement of X(124)
X(109) = X(I)-Ceva conjugate of X(J) for these (I,J): (59,56), (162,108)
X(109) = cevapoint of X(65) and X(513)
X(109) = X(I)-cross conjugate of X(J) for these (I,J): (56,59), (513,58)
X(109) = crosspoint of X(110) and X(162)
X(109) = crosssum of X(I) and X(J) for these (I,J): (523,656), (652,663)
X(109) = crossdifference of every pair of points on line X(11)X(1146)
X(109) = X(I)-aleph conjugate of X(J) for these (I,J): (100,1079), (162,580), (651,223)
X(109) = X(I)-beth conjugate of X(J) for these (I,J): (21,104), (59,109), (100,100), (110,109), (765,109), (901,109)
X(109) = trilinear product of X(1381) and X(1382)


X(110) = FOCUS OF KIEPERT PARABOLA

Trilinears       csc(B - C) : csc(C - A) : csc(A - B)
                        = a/(b2 - c2) : b/(c2 - a2) : c/(a2 - b2)

Barycentrics  a2/(b2 - c2) : b2/(c2 - a2) : c2/(a2 - b2)

X(110) - circumcircle-antipode of X(74)
X(110) = isogonal conjugate of the isotomic conjugate of X(99)
X(110) = Ψ(X(6), X(3))
X(110) = Feuerbach point of the tangential triangle if ABC is acute; otherwise, a vertex of the Feuerbach triangle of the tangential triangle.
X(110) is the center of the rectangular hyperbola that passes through these points: X(3), X(6), X(155), X(159), X(195), X(399), X(2917), and the vertices of the tangential triangle. (Randy Hutson, 9/23/2011)

J. W. Clawson, "Points on the circumcircle," American Mathematical Monthly 32 (1925) 169-174.

Roland H. Eddy and R. Fritsch, "The conics of Ludwig Kiepert: a comprehensive lesson in the geometry of the triangle," Mathematics Magazine 67 (1994) 188-205.

Benedetto Scimemi, "Paper-folding and Euler's Theorem Revisited," Forum Geometricorum.

Scimemi proves that if the Euler line is reflected in every side of triangle ABC, then the three reflections concur in X(110).

X(110) lies on these lines:
1,60   2,98   3,74   4,113   5,49   6,111   11,215   20,146   21,104   22,154   23,323   24,155   27,917   28,915   30,477   31,593   32,729   39,755   58,106   65,229   67,141   69,206   81,105   86,675   97,418   99,690   100,643   101,163   102,283   107,648   108,162   143,195   187,352   190,835   249,512   250,520   251,694   274,767   324,436   351,526   353,574   373,575   376,541   476,523   525,935   560,715   595,849   668,839   669,805   670,689   681,823   685,850   789,799   859,953

X(110) is the {X(5),X(49)}-harmonic conjugate of X(54). For a list of other harmonic conjugates of X(110), click Tables at the top of this page.

X(110) = midpoint of X(I) and X(J) for these (I,J): (3,399), (20,146), (23,323), (1495,3292)
X(110) = reflection of X(I) in X(J) for these (I,J): (3,1511), (4,113), (23,1495), (67,141), (74,3), (265,5), (382,1539), (895,6), (1177,206)

X(110) = isogonal conjugate of X(523)
X(110) = isotomic conjugate of X(850)
X(110) = inverse of X(2) in the Brocard circle
X(110) = complement of X(3448)
X(110) = anticomplement of X(125)
X(110) = X(I)-Ceva conjugate of X(J) for these (I,J): (249,6), (250,3)
X(110) = cevapoint of X(I) and X(J) for these (I,J): (3,520), (5,523), (6,512), (141,525)

X(110) = X(I)-cross conjugate of X(J) for these (I,J):
(1,59), (3,250), (6,249), (109,162), (351,111), (512,6), (520,3), (523,54), (526,74)

X(110) = crosssum of X(I) and X(J) for these (I,J): (2,148), (512,647), (520,647)
X(110) = crossdifference of every pair of points on line X(115)X(125)
X(110) = X(I)-Hirst inverse of X(J) for these (I,J): (1,245), (2,125), (3,246), (4,247)
X(110) = X(I)-beth conjugate of X(J) for these (I,J): (21,759), (643,643)


X(111) = PARRY POINT

Trilinears       a/(2a2 - b2 - c2) : b/(2b2 - c2 - a2) : c/(2c2 - a2 - b2)
Barycentrics  a2/(2a2 - b2 - c2) : b2/(2b2 - c2 - a2) : c2/(2c2 - a2 - b2)

X(111) = Λ(X(2), X(6))

X(111) lies on these lines:
2,99   6,110   23,187   25,112   37,100   42,101   107,393   182,353   230,476   251,827   308,689   352,511   385,892   468,935   512,843   647,842   694,805   931,941

X(111) = reflection of X(1296) in X(3)
X(111) = isogonal conjugate of X(524)
X(111) = isotomic conjugate of X(3266)
X(111) = inverse-in-Brocard-circle of X(353)
X(111) = anticomplement of X(126)
X(111) = cevapoint of X(6) and X(187)
X(111) = X(I)-cross conjugate of X(J) for these (I,J): (23,251), (187,6), (351,110)
X(111) = crossdifference of every pair of points on line X(351)X(690)


X(112) = Ψ(ORTHOCENTER, SYMMEDIAN POINT)

Trilinears       a/(sin 2B - sin 2C) : b/(sin 2C - sin 2A) : c/(sin 2A - sin 2B)
                        = f(a,b,c) : f(b,c,a) : f(c,a,b) where f(a,b,c) = a/[(b2 - c2)(b2 + c2 - a2)]

Barycentrics  a2/(sin 2B - sin 2C) : b2/(sin 2C - sin 2A) : c2/(sin 2A - sin 2B)

X(112) = Ψ(X(4), X(6))

If the line X(4)X(6) is reflected in every side of triangle ABC, then the reflections concur in X(112). (Randy Hutson, 9/23/2011)

X(112) lies on these lines:
2,127   4,32   6,74   19,759   25,111   27,675   28,105   33,609   50,477   54,217   58,103   99,648   100,162   102,284   104,1108   109,163   186,187   230,403   250,691   251,427   286,767   376,577   393,571   523,935   789,811

X(112) = reflection of X(I) in X(J) for these (I,J): (4,132), (1297,3)
X(112) = isogonal conjugate of X(525)
X(112) = anticomplement of X(127)
X(112) = X(I)-Ceva conjugate of X(J) for these (I,J): (249,24), (250,25)
X(112) = cevapoint of X(I) and X(J) for these (I,J): (32,512), (427,523)
X(112) = X(I)-cross conjugate of X(J) for these (I,J): (25,250), (512,4), (523,251)
X(112) = crossdifference of every pair of points on line X(122)X(125)
X(112) = barycentric product of X(1113) and X(1114)



leftri Centers 113-139 rightri
lie on the nine-point circle.

Suppose that X is a point on the nine-point circle, and let X' be the reflection of X in the orthocenter, H. Then X is the anticenter of the cyclic quadrilateral ABCX'. Let HA be the orthocenter of triangle BCX, Let HB be the orthocenter of CAX, and let HC be the orthocenter of triangle ABX. Then the quadrilateral HHAHBHC is homothetic to and congruent to the cyclic quadrilateral ABCX', and X is the center of homothety. (Randy Hutson, 9/23/2011)

underbar


X(113) = JERABEK ANTIPODE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = sin B sin C [(sin C)/(cos C - 2 cos A cos B) + (sin B)/(cos B - 2 cos A cos C)]

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where
                        g(A,B,C) = (sin C)/(cos C - 2 cos A cos B) + (sin B)/(cos B - 2 cos A cos C)

                        = h(a,b,c) : h(b,c,a) : h(c,a,b),
                        where h(a,b,c) = b2/(b2SB - 2SASC) + c2/(c2SC - 2SASB),
                        SA = (b2 + c2 - a2)/2, and SB and SC are defined cyclically (Peter J. C. Moses, 3/2003)

X(113) = nine-point-circle-antipode of X(125)
X(113) = X(74)-of-medial-triangle
X(113) = X(104)-of-orthic-triangle
X(113) = X(186)-of-X(4)-Brocard-triangle
X(113) = center of rectangular circumhyperbola that passes through X(110)
X(113) = center of rectangular hyperbola {X(3),X(4),X(110),X(155),X(1351),X(1352),X(2574,X(2575)}
X(113) = perpsector of circumconic centered at X(3003)
X(113) = inverse-in-polar-circle-of X(1300)
X(113) = inverse-in-{circumcircle, nine-point circle}-inverter of X(1302)
X(113) = anticenter of cyclic quadrilateral ABCX(110)
X(113) = Λ(X(2),X(3))-with-respect-to-orthic-triangle

Let A'B'C' be the orthic triangle. Let L be the line through A' parallel to the Euler line, and define M and N cyclically. Let L' be the reflection of L in sideline BC, and define M' and N' cyclically. The lines L', M', N' concur in X(113). (Randy Hutson, August 26, 2014)

Let A'B'C' be the orthic triangle. Let MA be the reflection of the orthic axis in line B'C', and define Let MB and Let MC cyclically. Let A'' = Let MB∩MC, and define B'' and C'' cyclically. The lines A'A'', B'B'' C'C'' concur in X(113). (Randy Hutson, August 26, 2014)

Let A'B'C' be the orthic triangle. Let NA be the orthic axis of AB'C', and define NB and NC cyclically. Let A'' = NB∩NC, B'' = NC∩AC, C'' = NA∩BC. Then triangle A''B''C'' is inversely similar to ABC, with similitude center X(6), and the lines A'A'', B'B'', C'C'' concur in X(113). Also, X(113) = X(3)-of-A''B''C''. (Randy Hutson, August 26, 2014)

X(113) lies on these lines:
2,74   3,122   4,110   5,125   6,13   11,942   52,135   114,690   123,960   127,141   137,546

X(113) = midpoint of X(I) and X(J) for these (I,J): (4,110), (74,146), (265,399), (1553,3258)
X(113) = reflection of X(I) in X(J) for these (I,J): (52,1112), (125,5)
X(113) = complementary conjugate of X(30)
X(113) = X(i)-Ceva conjugate of X(j) for these (i,j): (4,30), (2,3003)
X(113) = crosspoint of X(4) and X(403)
X(113) = crossdifference of any two points on line X(526)X(686)


X(114) = KIEPERT ANTIPODE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc[b sec(B + ω) + c sec(C + ω)]
                        = cos(B - C) cos 2ω - sin ω sin(A + ω) (Peter J. C. Moses, 9/12/03)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = b sec(B + ω) + c sec(C + ω)

X(114) = nine-point-circle-antipode of X(115)
X(114) = X(98)-of-medial triangle
X(114) = X(103)-of-orthic triangle.

X(114) lies on these lines:
2,98   3,127   4,99   5,39   25,135   52,211   113,690   132,684   136,427   325,511   381,543

X(114) = isogonal conjugate of X(2065)
X(114) = midpoint of X(I) and X(J) for these (I,J): (4,99), (98,147)
X(114) = reflection of X(I) in X(J) for these (I,J): (3,620), (115,5)
X(114) = complementary conjugate of X(511)
X(114) = X(I)-Ceva conjugate of X(J) for these (I,J): (2,230), (4,511)
X(114) = crosspoint of X(2) and X(325)
X(114) = orthojoin of X(230)


X(115) = CENTER OF KIEPERT HYPERBOLA

Trilinears       bc(b2 - c2)2 : ca(c2 - a2)2 : ab(a2 - b2)2
                        = cos A - 2 cos(B - C) + cot ω sin A (Peter J. C. Moses, 9/12/03)

Barycentrics  (b2 - c2)2 : (c2 - a2)2 : (a2 - b2)2

X(115) = 2(tan ω sin 2ω)*X(5) - X(39)

If you have The Geometer's Sketchpad, you can view Kiepert Hyperbola, showing X(115).

X(115) lies on the nine-point circle
X(115) = X(99)-of-medial triangle
X(115) = X(101)-of-orthic triangle

Roland H. Eddy and R. Fritsch, "The conics of Ludwig Kiepert: a comprehensive lesson in the geometry of the triangle," Mathematics Magazine 67 (1994) 188-205.

X(115) lies on these lines:
2,99   4,32   5,39   6,13   11,1015   30,187   50,231   53,133   76,626   116,1086   120,442   125,245   127,338   128,233   129,389   131,216   232,403   316,385   325,538   395,530   396,531   593,1029   804,1084

X(115) = midpoint of X(I) and X(J) for these (I,J): (4,98), (13,14), (99,148), (316,385)
X(115) = reflection of X(I) in X(J) for these (I,J): (99,620), (114,5), (187,230), (325,625)
X(115) = isogonal conjugate of X(249)
X(115) = inverse-in-orthocentroidal-circle of X(6)
X(115) = complementary conjugate of X(512)
X(115) = X(I)-Ceva conjugate of X(J) for these (I,J): (2,523), (4,512), (338,125)
X(115) = crosspoint of X(I) and X(J) for these (I,J): (2,523), (68,525)
X(115) = crosssum of X(I) and X(J) for these (I,J): (6,110), (24,112), (163,849)
X(115) = crossdifference of every pair of points on line X(110)X(351)
X(115) = X(2)-Hirst inverse of X(148)


X(116) = MIDPOINT OF X(4) AND X(103)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b) where
                        f(a,b,c) = bc[(b - c)2(b2 + bc + c2 - ab - ac)]

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b) where
                        g(a,b,c) = (b - c)2(b2 + bc + c2 - ab - ac)

X(116) lies on the nine-point circle
X(116) = X(101)-of-medial triangle.

X(116) lies on these lines: 2,101   4,103   5,118   10,120   115,1086   119,142   121,141   124,928

X(116) = midpoint of X(I) and X(J) for these (I,J): (4,103), (101,150)
X(116) = reflection of X(118) in X(5)
X(116) = complementary conjugate of X(514)
X(116) = X(4)-Ceva conjugate of X(514)


X(117) = MIDPOINT OF X(4) AND X(109)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = g(b,c,a) + g(c,b,a), and
                        g(b,c,a) = b2c/[c(sec B - sec C) + a(sec B - sec A)]

Barycentrics  h(a,b,c) : h(b,c,a) : h(c,a,b) where h(a,b,c) = af(a,b,c)

X(117) lies on the nine-point circle
X(117) = X(102)-of-medial triangle.

X(117) lies on these lines: 2,102   4,109   5,124   10,123   11,65   118,928   136,407

X(117) = midpoint of X(I) and X(J) for these (I,J): (4,109), (102,151)
X(117) = reflection of X(124) in X(5)
X(117) = complementary conjugate of X(515)
X(117) = X(4)-Ceva conjugate of X(515)


X(118) = MIDPOINT OF X(4) AND X(101)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = g(b,c,a) + g(c,b,a), and
                        g(b,c,a) = b3c/[(b - c) cot A + (b - a) cot C]

Barycentrics  h(a,b,c) : h(b,c,a) : h(c,a,b) where h(a,b,c) = af(a,b,c)

X(118) lies on the nine-point circle
X(118) = X(103)-of-medial triangle.

X(118) lies on these lines: 2,103   4,101   5,116   11,226   117,928   122,440   136,430   381,544   516,910

X(118) = midpoint of X(I) and X(J) for these (I,J): (4,101), (103,152)
X(118) = reflection of X(116) in X(5)
X(118) = complementary conjugate of X(516)
X(118) = X(4)-Ceva conjugate of X(516)


X(119) = FEUERBACH ANTIPODE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (csc A)(-1 + cos B + cos C)[sin 2B + sin 2C + 2(-1 + cos A)(sin B + sin C)]

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B) where
                        g(A,B,C) = (-1 + cos B + cos C)[sin 2B + sin 2C + 2(-1 + cos A)(sin B + sin C)]

X(119) = nine-point-circle-antipode of X(11)
X(119) = X(104)-of-medial triangle.

X(119) lies on these lines:
1,5   2,104   3,123   4,100   10,124   116,142   125,442   135,431   136,429   214,515   381,528   517,908

X(119) = midpoint of X(I) and X(J) for these (I,J): (4,100), (104,153)
X(119) = reflection of X(I) in X(J) for these (I,J): (11,5), (3,3035)
X(119) = complement of X(104)
X(119) = complementary conjugate of X(517)
X(119) = X(4)-Ceva conjugate of X(517)


X(120) = X(105)-OF-MEDIAL-TRIANGLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = bc[2abc - (b + c)(a2 + (b - c)2)](b2 + c2 - ab -ac)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b) where g(a,b,c) = [2abc - (b + c)(a2 + (b - c)2)](b2 + c2 - ab -ac)

X(120) lies on the nine-point circle
X(120) = X(105)-of-medial triangle.

X(120) lies on these lines: 2,11   10,116   12,85   115,442

X(120) = complementary conjugate of X(518)
X(120) = X(4)-Ceva conjugate of X(518)


X(121) = X(106)-OF-MEDIAL-TRIANGLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = bc(b + c - 2a)[b3 + c3 + a(b2 + c2) - 2bc(b + c)]

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b) where g(a,b,c) = (b + c - 2a)[b3 + c3 + a(b2 + c2) - 2bc(b + c)]

X(121) lies on the nine-point circle
X(121) = X(106)-of-medial triangle.

X(121) lies on these lines: 2,106   10,11   116,141

X(121) = complementary conjugate of X(519)
X(121) = X(4)-Ceva conjugate of X(519)


X(122) = X(107)-OF-MEDIAL-TRIANGLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (b2 - c2)2(cos A - cos B cos C) cot2A

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b) where g(a,b,c) = a(b2 - c2)2(cos A - cos B cos C) cot2A

X(122) lies on the nine-point circle
X(122) = X(107)-of-medial triangle
X(122) = center of the rectangular hyperbola that passes through A, B, C, and X(20)

X(122) lies on these lines: 2,107   3,113   5,133   118,440   125,684   138,233

X(122) = reflection of X(133) in X(5)
X(122) = complementary conjugate of X(520)
X(122) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,520), (253,525)
X(122) = crosssum of X(I) and X(J) for these (I,J): (64,1301), (112,154)
X(122) = crosspoint of X(253) and X(525)
X(122) = crossdifference of every pair of points on line X(112)X(1301)


X(123) = X(108)-OF-MEDIAL-TRIANGLE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (csc A)(sec B - sec C)[(sec A)(sin2B - sin2C) + sin C tan C - sin B tan B]

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B) where
                        g(A,B,C) = (sec B - sec C)[(sec A)(sin2B - sin2C) + sin C tan C - sin B tan B]

X(123) lies on the nine-point circle
X(123) = X(108)-of-medial triangle.

X(123) lies on these lines: 2,108   3,119   10,117   113,960

X(123) = complementary conjugate of X(521)
X(123) = X(4)-Ceva conjugate of X(521)


X(124) = X(109)-OF-MEDIAL-TRIANGLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = bc(b + c - a)(b - c)2[(b + c)(b2 + c2 - a2 - bc) + abc]

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where
                        g(a,b,c) = (b + c - a)(b - c)2 [(b + c)(b2 + c2 - a2 - bc) + abc]

X(124) lies on the nine-point circle
X(124) = X(109)-of-medial triangle
X(124) = center of the rectangular hyperbola that passes through A, B, C, and X(58)

X(124) lies on these lines: 2,109   4,102   5,117   10,119   116,928

X(124) = midpoint of X(4) and X(102)
X(124) = reflection of X(117) in X(5)
X(124) = complementary conjugate of X(522)
X(124) = X(4)-Ceva conjugate of X(522)


X(125) = CENTER OF JERABEK HYPERBOLA

Trilinears       cos A sin2(B - C) : cos B sin2(C - A) : cos C sin2(A - B)
                        = (sec A)(c cos C - b cos B)2 : (sec B)(a cos A - c cos C)2 : (sec C)(b cos B - a cos A)2
                        = bc(b2 + c2 - a2)(b2 - c2)2 : ca(c2 + a2 - b2)(c2 - a2)2 : ab(a2 + b2 - c2)(a2 - b2)2

Barycentrics  (sin 2A)[sin(B - C)]2 : (sin 2B)[sin(C - A)]2 : (sin 2C)[sin(A - B)]2

X(125) lies on the nine-point circle
X(125) = X(110)-of-medial triangle
X(125) = X(100)-of-orthic triangle, if ABC is acute

Roland H. Eddy and R. Fritsch, "The conics of Ludwig Kiepert: a comprehensive lesson in the geometry of the triangle," Mathematics Magazine 67 (1994) 188-205.

X(125) is the pole of the Fermat axis with respect to the Dao-Moses-Telv circle. (Randy Hutson, December 14, 2014)

X(125) lies on these lines:
2,98   3,131   4,74   5,113   6,67   51,132   68,1092   69,895   115,245   119,442   122,684   126,141   128,140   136,338   381,541   511,858

X(125) = midpoint of X(I) and X(J) for these (I,J): (3,265), (4,74), (6,67), (110,3448)
X(125) = reflection of X(I) in X(J) for these (I,J): (113,5), (185,974), (1495,468), (1511,140), (1539,546)
X(125) = isogonal conjugate of X(250)
X(125) = inverse-in-Brocard-circle of X(184)
X(125) = complement of X(110)
X(125) = complementary conjugate of X(523)
X(125) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,523), (66,512), (68,520), (69,525), (338,115)
X(125) = crosspoint of X(I) and X(J) for these (I,J): (4,523), (69,525), (338,339)
X(125) = crosssum of X(I) and X(J) for these (I,J): (3,110), (25,112), (162,270), (1113,1114)
X(125) = crossdifference of every pair of points on line X(110)X(112)
X(125) = X(115)-Hirst inverse of X(868)
X(125) = X(2)-line conjugate of X(110)


X(126) = X(111)-OF-MEDIAL-TRIANGLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = bc(2a2 - b2 - c2)[b4 + c4 + a2(b2 + c2) - 4b2c2]

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b) where g(a,b,c) = (2a2 - b2 - c2)[b4 + c4 + a2(b2 + c2) - 4b2c2]

X(126) lies on the nine-point circle
X(126) = X(111)-of-medial triangle.

X(126) lies on these lines: 2,99   125,141   625,858

X(126) = complement of X(111)
X(126) = complementary conjugate of X(524)
X(126) = X(4)-Ceva conjugate of X(524)


X(127) = X(112)-OF-MEDIAL-TRIANGLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = bc(sin 2B - sin 2C)[(b2 - c2)sin 2A - b2sin 2B + c2sin 2C]

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where
                        g(a,b,c) = (sin 2B - sin 2C)[(b2 - c2)sin 2A - b2sin 2B + c2sin 2C]

X(127) lies on the nine-point circle
X(127) = X(112)-of-medial triangle
X(127) = center of the rectangular hyperbola that passes through A, B, C, and X(22)

X(127) lies on these lines: 2,112   3,114   5,132   113,141   115,338   133,381   125,140

X(127) = reflection of X(132) in X(5)
X(127) = complement of X(112)
X(127) = anticomplementary conjugate of X(525)
X(127) = X(4)-Ceva conjugate of X(525)


X(128) = X(74)-OF-ORTHIC-TRIANGLE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (sec A)(cos 2B + cos 2C)(1 + 2 cos 2A)(cos 2A + 2 cos 2B cos 2C)

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B) where g(A,B,C) = (sin A) f(A,B,C)

X(128) lies on the nine-point circle
X(128) = X(74)-of-orthic triangle.

X(128) lies on these lines: 5,137   52,134   53,139   115,233   125,140

X(128) = reflection of X(137) in X(5)
X(128) = X(2)-Ceva conjugate of X(231)
X(128) = orthojoin of X(231)


X(129) = X(98)-OF-ORTHIC-TRIANGLE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (sec A)(sin 2A)(sin 2B + sin 2C) s(A,B,C) t(A,B,C),
                        s(A,B,C) = sin4(2B) + sin4(2C) - sin2(2A) sin2(2B) - sin2(2A) sin2(2C),
                        t(A,B,C) = sin4(2A) + sin2(2A) u(A,B,C) + v(A,B,C),
                        u(A,B,C) = sin 2B sin 2C - sin2(2B) - sin2(2C),
                        v(A,B,C) = (sin 2B sin 2C)(sin 2B - sin 2C)2

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B) where g(A,B,C) = (sin A) f(A,B,C)

X(129) lies on the nine-point circle
X(129) = X(98)-of-orthic triangle.

X(129) lies on these lines: 5,130   51,137   52,139   115,389

X(129) = reflection of X(130) in X(5)


X(130) = X(99)-OF-ORTHIC-TRIANGLE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (sin A)(sin 2B + sin 2C)[(sin 2B - sin 2C)2][sin2(2A) + sin 2B sin 2C]

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A) f(A,B,C)

X(130 lies on the nine-point circle
X(130) = X(99)-of-orthic triangle
X(130) = center of the rectangular hyperbola that passes through A, B, C, and X(51)

X(130) lies on these lines: 5,129   51,138

X(130) = reflection of X(129) in X(5)


X(131) = INTERSECTION OF LINES X(3)X(125) AND X(4)X(135)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (sec A)[2T - S(sec 2B + sec 2C)](T - S sec 2A),
                        S = sin 2A + sin 2B + sin 2C, T = tan 2A + tan 2B + tan 2C

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A) f(A,B,C)

X(131) lies on the nine-point circle
X(131) = X(102)-of-orthic triangle if ABC is acute.

X(131) lies on these lines: 3,125   4,135   5,136   115,216

X(131) = reflection of X(136) in X(5)


X(132) = INTERSECTION OF LINES X(2)X(107) AND X(4)X(32)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (sec A) u(A,B,C) v(A,B,C),
                        u(A,B,C) = [sin2(2A) + (sin 2B - sin 2C)2 + (sin 2A)(sin 2A - sin 2B - sin 2C)],
                        v(A,B,C) = [sin2(2B) + sin2(2C) - (sin 2A sin 2B) - (sin 2A sin 2C)]

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A) f(A,B,C)

X(132) lies on the nine-point circle
X(132) = X(105)-of-orthic triangle if ABC is acute

X(132) lies on these lines: 2,107   4,32   5,127   25,136   51,125   114,684   137,428   147,648

X(132) = midpoint of X(4) and X(112)
X(132) = reflection of X(127) in X(5)
X(132) = X(I)-Ceva conjugate of X(J) for these (I,J): (2,232), (4,1503)
X(132) = X(4)-line conjugate of X(248)
X(132) = crossdifference of every pair of points on line X(248)X(684)


X(133) = INTERSECTION OF LINES X(4)X(74) AND X(5)X(122)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (sec A) u(A,B,C) v(A,B,C),
                        u(A,B,C) = (sin 2B - sin 2C)2 + sin 2A sin 2B - sin 2A sin 2C - 2 sin 2B sin 2C,
                        v(A,B,C) = 2 sin 2A - sin 2B - sin 2C

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A) f(A,B,C)

X(133) lies on the nine-point circle
X(133) = X(106)-of-orthic triangle is ABC is acute.

X(133) lies on these lines: 4,74   5,122   53,115   127,381   136,235

X(133) = midpoint of X(4) and X(107)
X(133) = reflection of X(122) in X(5)


X(134) = X(107)-OF-ORTHIC-TRIANGLE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (sec A) u(A,B,C) [v(B,C,A) - v(C,B,A)],
                        u(A,B,C) = (sin 2A)[sin2(2B) - sin2(2C)][sin2(2B) + sin2(2C) - sin2(2A)]2,
                        v(B,C,A) = sin 2C [sin2(2A) - sin2(2B)][sin2(2A) + sin2(2B) - sin2(2C)]2

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A) f(A,B,C)

X(134) lies on the nine-point circle
X(134) = X(107)-of-orthic triangle
X(134) = center of the rectangular hyperbola that passes through A, B, C, and X(52)

X(134) lies on this line: 52,128


X(135) = INTERSECTION OF LINE X(4)X(131) AND X(25)X(114)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (sec A)[(sin 2B)/(sec 2C - sec 2A) + (sin 2C)/(sec 2A - sec 2B)]

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where
           &nbnbsp;            g(A,B,C) = (tan A)[(sin 2B)/(sec 2C - sec 2A) + (sin 2C)/(sec 2A - sec 2B)]

X(135) lies on the nine-point circle
X(135) = X(108)-of-orthic-triangle if ABC is acute
X(135) = center of the rectangular hyperbola that passes through A, B, C, and X(24)

X(135) lies on these lines: 4,131   25,114   52,113   119,431


X(136) = INTERSECTION OF LINE X(4)X(110) AND X(25)X(132)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (sec A)[(sin 2B - sin 2C)2](sin 2B + sin 2C - sin 2A) u(A,B,C),
                        u(A,B,C) = [sin2(2B) + sin2(2C) - sin2(2A)]

Barycentrics  af(A,B,C) : bf(B,C,A) : cf(C,A,B)

X(136) lies on the nine-point circle
X(136) =X(109)-of-orthic triangle if ABC is acute
X(136) = center of the rectangular hyperbola that passes through A, B, C, and X(93)

X(136) lies on these lines:
2,925   4,110   5,131   25,132   68,254   114,427   117,407   118,430   119,429   125,338   127,868   133,235

X(136) = reflection of X(131) in X(5)
X(136) = complement of X(925)
X(136) = complementary conjugate of X(924)
X(136) = X(254)-Ceva conjugate of X(523)


X(137) = X(110)-OF-ORTHIC-TRIANGLE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (sec A)(sin 2B + sin 2C)[(sin 2B - sin 2C)2] u(A,B,C),
                        u(A,B,C) = [sin2(2A) - sin2(2B) - sin2(2C) - sin 2B sin 2C]

Barycentrics  af(A,B,C) : bf(B,C,A) : cf(C,A,B)

X(137) lies on the nine-point circle
X(137) = X(110)-of-orthic triangle
X(137) = center of the rectangular hyperbola that passes through A, B, C, X(5), and X(53)

X(137) lies on these lines: 5,128   51,129   53,138   113,546   132,428

X(137) = reflection of X(128) in X(5)
X(137) = complement of X(930)
X(137) = X(4)-Ceva conjugate of X(1510)
X(137) = crosssum of X(252) and X(930)


X(138) = X(111)-OF-ORTHIC-TRIANGLE

Trilinears       (v + w) sec A : (w + u) sec B : (u + v) sec C, where
                        u = u(A,B,C) = (sin 2A)/(2 sin22A - sin22B - sin22C), v = u(B,C,A), w = u(C,A,B)

Barycentrics  (v + w) tan A : (w + u) tan B : (u + v) tan C

X(138) lies on the nine-point circle
X(138) = X(111)-of-orthic triangle

X(138) lies on these lines: 51,130   53,137   122,233


X(139) = X(112)-OF-ORTHIC-TRIANGLE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (sec A)(sin 2B + sin 2C)[(sin 2B - sin 2C)2][sin2(2B) + sin2(2C) - sin2(2A)] u(A,B,C),
                        u(A,B,C) = (sin 2B)4 + (sin 2C)4 - (sin 2A)4 + (sin 2B sin 2C)[sin2(2B) + sin2(2C) - sin2(2A)]

Barycentrics  af(A,B,C) : bf(B,C,A) : cf(C,A,B)

X(139) lies on the nine-point circle
X(139) = X(112) of the orthic triangle

X(139) lies on these lines: 52,129   53,128



leftri Centers 140- 170 rightri
113- 127, 140- 143: centers of the medial triangle
128- 139: centers of the orthic triangle
144- 153: centers of the anticomplementary triangle
154- 157, 159- 163: centers of the tangential triangle
164- 170: centers of the excentral triangle

underbar

X(140) = MIDPOINT OF X(3) AND X(5)

Trilinears       2 cos A + cos(B - C) : 2 cos B + cos(C - A) : 2 cos C + cos(A - B)
                     = cos A + 2 sin B sin C : cos B + 2 sin C sin A : cos C + 2 sin A sin B
                     = 3 cos A + 2 cos B cos C : 3 cos B + 2 cos C cos A : 3 cos C + 2 cos A cos B
                     = 2 sec A + 3 sec B sec C : 2 sec B + 3 sec C sec A : 2 sec C + 3 sec A sec B
                     = f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = bc[b cos(C - A) + c cos(B - A)]

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b) where g(a,b,c) = b cos(C - A) + c cos(B - A)

X(140) = crosspoint of the two Napoleon points
X(140) = X(5)-of-medial triangle
X(140) = centroid of the quadrilateral ABCX(3)

Let A' be the midpoint between A and X(3), and define B' and C' cyclically; the triangle A'B'C' is homothetic to the medial triangle, and the center of homothety is X(140). Let A'' be the centroid of the triangle BCX(3), and define B'' and C'' cyclically; then A''B''C'' is homothetic to ABC, and the center of homothety is X(140). Also, X(140) is the center of the conic consisting of the centers of all the conics which pass through A, B, C, and X(3). (Randy Hutson, 9/23/2011)

X(140) lies on these lines:
2,3   10,214   11,35   12,36   15,18   16,17   39,230   54,252   55,496   56,495   61,395   62,396   95,340   125,128   141,182   143,511   195,323   298,628   299,627   302,633   303,634   343,569   371,615   372,590   524,575   576,597   601,748   602,750   618,630   619,629

X(140) is the {X(2),X(3)}-harmonic conjugate of X(5). For a list of other harmonic conjugates of X(140), click Tables at the top of this page.

X(140) = midpoint of X(I) and X(J) for these (I,J): (3,5), (141,182), (2883, 3357)
X(140) = reflection of X(I) in X(J) for these (I,J): (546,5), (547,2), (548,3)
X(140) = inverse-in-orthocentroidal-circle of X(1656)
X(140) = isogonal conjugate of X(1173)
X(140) = complement of X(5)
X(140) = complementary conjugate of X(1209)
X(140) = X(2)-Ceva conjugate of X(233)
X(140) = crosspoint of X(I) and X(J) for these (I,J): (2,95), (17,18)
X(140) = crosssum of X(I) and X(J) for these (I,J): (6,51), (61,62)


X(141) = COMPLEMENT OF SYMMEDIAN POINT

Trilinears       bc(b2 + c2) : ca(c2 + a2) : ab(a2 + b2)
                         = csc2A sin(A + ω) : csc2B sin(B + ω) : csc2C sin(C + ω)

Barycentrics  b2 + c2 : c2 + a2 : a2 + b2

X(141) = X(6)-of-medial triangle

X(141) lies on these lines:
2,6   3,66   5,211   10,142   37,742   39,732   45,344   53,264   67,110   75,334   76,698   95,287   99,755   113,127   116,121   125,126   140,182   239,319   241,307   308,670   311,338   317,458   320,894   384,1031   441,577   498,611   499,613   523,882   542,549   575,629   997,1060

X(141) is the {X(2),X(69)}-harmonic conjugate of X(6). For a list of other harmonic conjugates of X(141), click Tables at the top of this page.

X(141) = midpoint of X(I) and X(J) for these (I,J): (1,3416), (6,69), (8,3242), (66,159), (67,110), (69,3313), (1843,3313) (2930, 3448)
X(141) = reflection of X(I) in X(J) for these (I,J): (182,140), (597,2), (1353,575), (1386,1125)
X(141) = isogonal conjugate of X(251)
X(141) = isotomic conjugate of X(83)
X(141) = inverse-in-nine-point-circle of X(625)
X(141) = complement of X(6)
X(141) = complementary conjugate of X(2)
X(141) = X(I)-Ceva conjugate of X(J) for these (I,J): (2,39), (67,524), (110,525)
X(141) = X(39)-cross conjugate of X(427)
X(141) = crosspoint of X(2) and X(76)
X(141) = crosssum of X(6) and X(32)
X(141) = X(39)-Hirst inverse of X(732)
X(141) = X(645)-beth conjugate of X(141)


X(142) = COMPLEMENT OF X(9)

Trilinears       b + c - [(b - c)2]/a : c + a - [(c - a)2]/b : a + b - [(a - b)2]/c
Barycentrics  ab + ac - (b - c)2 : bc + ba - (c - a)2 : ca + cb - (a - b)2

X(142) = X(9)-of- medial triangle
X(142) = centroid of the set {X(1), X(4), X(7), X(40)}

Let A' be the midpoint between A and X(7), and define B' and C' cyclically; the triangle A'B'C' is homothetic to the medial triangle, and the center of homothety is X(142). (Randy Hutson, 9/23/2011)

X(142) lies on these lines: 1,277   2,7   3,516   5,971   10,141   37,1086   86,284   116,119   214,528   269,948   377,950   474,954

X(142) is the {X(2),X(7)}-harmonic conjugate of X(9). For a list of other harmonic conjugates, click Tables at the top of this page.

X(142) = midpoint of X(I) and X(J) for these (I,J): (7,9), (8,3243), (100,3254)
X(142) = reflection of X(1001) in X(1125)
X(142) = isogonal conjugate of X(1174)
X(142) = complement of X(9)
X(142) = X(100)-Ceva conjugate of X(514)
X(142) = crosspoint of X(2) and X(85)
X(142) = crosssum of X(6) and X(41)
X(142) = X(190)-beth conjugate of X(142)


X(143) = NINE-POINT CENTER OF ORTHIC TRIANGLE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (sec A)[cos(2C - 2A) + cos(2A - 2B)]

Trilinears       g(A,B,C) : g(B,C,A) : g(C,A,B), where
                        g(A,B,C) = [1 - 2 cos(2A)]cos(B - C)]

Trilinears       h(A,B,C) : h(B,C,A) : h(C,A,B), where
                        h(A,B,C) = sec A cos(3A) cos(B - C) (Manol Iliev, 4/01/07)

Barycentrics  k(A,B,C) : k(B,C,A) : k(C,A,B), where k(A,B,C) = (tan A)[cos(2C - 2A) + cos(2A - 2B)]

This point is the third of three Spanish Points developed by Antreas P. Hatzipolakis and Javier Garcia Capitan in 2009; see X(3567).

X(143) = X(5)-of-orthic triangle, if ABC is acute.
X(143) = insimilicenter of the circumcircle and the nine-point circle of the orthic triangle. (Peter Moses, July 1, 2009)

X(143) lies on these lines: 4,94   5,51   6,26   25,156   30,389   110,195   140,511   324,565

X(143) is the {X(51),X(52)}-harmonic conjugate of X(5). For a list of other harmonic conjugates, click Tables at the top of this page.

X(143) = midpoint of X(5) and X(52)
X(143) = isogonal conjugate of X(252)
X(143) = X(137)-cross conjugate of X(1510)


X(144) = ANTICOMPLEMENT OF X(7)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B),
                        where f(A,B,C) = (csc A)(tan B/2 + tan C/2 - tan A/2)

Barycentrics  tan B/2 + tan C/2 - tan A/2 : tan C/2 + tan A/2 - tan B/2 : tan A/2 + tan B/2 - tan C/2

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b),
                        where g(a,b,c) = 1/(a - b - c) + 1/(a - b + c) + 1/(a + b - c) (Peter J. C. Moses, 4/8/03)

X(144) = X(7)-of-anticomplementary triangle

X(144) lies on these lines:
2,7   8,516   20,72   21,954   69,190   75,391   100,480   145,192   219,347   220,279   320,344

X(144) is the {X(7),X(9)}-harmonic conjugate of X(2). For a list of other harmonic conjugates of X(144), click Tables at the top of this page.

X(144) = reflection of X(I) in X(J) for these (I,J): (7,9), (145,390), (149,1156)
X(144) = anticomplement of X(7)
X(144) = anticomplementary conjugate of X(3434)
X(144) = X(8)-Ceva conjugate of X(2)
X(144) = X(I)-beth conjugate of X(J) for these (I,J): (190,144), (645,346)


X(145) = ANTICOMPLEMENT OF NAGEL POINT

Trilinears       bc(3a - b - c) : ca(3b - c - a) : ab(3c - a - b)
Barycentrics  3a - b - c : 3b - c -a : 3c - a - b

X(145) = X(8)-of-anticomplementary-triangle

Let A' be the reflection of the midpoint of segment BC in X(1), and define B' and C' cyclically. The lines AA', BB', CC' concur in X(145). Let A'' be the reflection of the A in X(1), and define B'' and C'' cyclically. Let A'''B'''C''' be the intouch triangle. The lines A''A''', B''B''', C''C''' concur in X(145). (Randy Hutson, 9/23/2011)

Let OA be the circle tangent to side BC at its midpoint and to the circumcircle on the same side of BC as A. Define OB, OC cyclically. Then X(145) is the trilinear pole of the line of the excimilicenters (the Monge line) of OA, OB, OC. See the reference at X(1001).

X(145) is the {X(1),X(8)}-harmonic conjugate of X(2). For a list of other harmonic conjugates of X(145), click Tables at the top of this page.

X(145) lies on these lines: 1,2   4,149   6,346   20,517   21,956   37,391   56,100   72,452   81,1043   144,192   218,644   279,664   329,950   330,1002   377,1056   404,999   515,962

X(145) = midpoint of X(2) and X(3241)
X(145) = reflection of X(I) in X(J) for these (I,J): (3,1483), (4,1482), (8,1), (20,944), (100,1317), (144,390), (149,1320)
X(145) = isogonal conjugate of X(3445)
X(145) = anticomplement of X(8)
X(145) = anticomplementary conjugate of X(3436)
X(145) = X(7)-Ceva conjugate of X(2)
X(145) = crosssum of X(663) and X(1015)
X(145) = X(643)-beth conjugate of X(56)


X(146) = REFLECTION OF X(20) IN X(110)

Trilinears       bc(-avw + bwu + cuv) : ca(-bwu + cuv + avw) : ab(-cuv + avw + bwu), where
                        u = u(A,B,C) = cos A - 2 cos B cos C, v = u(B,C,A), w = u(C,A,B)

Barycentrics  -avw + bwu + cuv : -bwu + cuv + avw : -cuv + avw + bwu

X(146) = X(74)-of-anticomplementary triangle

X(146) lies on these lines: 2,74   4,94   20,110   30,323   147,690   148,193

X(146) is the {X(74),X(113)}-harmonic conjugate of X(2). For a list of harmonic conjugates, click Tables at the top of this page.

X(146) = reflection of X(I) in X(J) for these (I,J): (20,110), (74,113), (265,1539)
X(146) = anticomplementary conjugate of X(30)


X(147) = TARRY POINT OF ANTICOMPLEMENTARY TRIANGLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = bc[a8 + (b2 + c2)a6 - (2b4 + 3b2c2 + 2c4)a4
                        + (b6 + b4c2 + b2c4 + c6)a2 - b8 + b6c2 + b2c6 - c8]

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(147) = X(98)-of-anticomplementary triangle

X(147) lies on these lines: 1,150   2,98   4,148   20,99   132,648   146,690   684,804

X(147) is the {X(98),X(114)}-harmonic conjugate of X(2). For a list of harmonic conjugates, click Tables at the top of this page.

X(147) = reflection of X(I) in X(J) for these (I,J): (20,99), (98,114), (148,4), (385,1513)
X(147) = anticomplementary conjugate of X(511)
X(147) = X(325)-Ceva conjugate of X(2)


X(148) = STEINER POINT OF ANTICOMPLEMENTARY TRIANGLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = bc[a4 - (b2 - c2)2 + b2c2 - a2b2 - a2c2]

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = a4 - (b2 - c2)2 + b2c2 - a2b2 - a2c2

X(148) = X(99)-of-anticomplementary triangle

X(148) lies on these lines: 2,99   4,147   13,617   20,98   30,385   146,193   316,538

X(148) = reflection of X(I) in X(J) for these (I,J): (2,671), (20,98), (99,115), (147,4), (616,14), (617,13)
X(148) = anticomplementary conjugate of X(512)
X(148) = X(523)-Ceva conjugate of X(2)
X(148) = X(2)-Hirst inverse of X(115)


X(149) = REFLECTION OF X(20) IN X(104)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = bc[b3 + c3 - a3 + (a2 - bc)(b + c) + a(bc - b2 - c2)]

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where
                        g(a,b,c) = b3 + c3 - a3 + (a2 - bc)(b + c) + a(bc - b2 - c2)

X(149) = X(100)-of-anticomplementary-triangle

Let A' be the reflection of the midpoint of segment BC in X(11), and define B' and C' cyclically. The lines AA', BB', CC' concur in X(149). (Randy Hutson, 9/23/2011)

X(149) lies on these lines: 2,11   4,145   8,80   20,104   151,962   377,1058   404,496

X(149) is the {X(11),X(100)}-harmonic conjugate of X(2). For a list of harmonic conjugates, click Tables at the top of this page.

X(149) = reflection of X(I) in X(J) for these (I,J): (3,1484), (8,80), (20,104), (100,11), (144,1156), (145,1320), (153,4)
X(149) = isogonal conjugate of X(3446)
X(149) = anticomplementary conjugate of X(513)


X(150) = REFLECTION OF X(20) IN X(103)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = bc[b4 + c4 - a4 + a(bc2 +cb2 - b3 - c3) - bc(a2 + b2 + c2) + (b + c)a3]

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where
                        g(a,b,c) = b4 + c4 - a4 + a(bc2 +cb2 - b3 - c3) - bc(a2 + b2 + c2) + (b + c)a3

X(150) = X(101)-of-anticomplementary triangle

X(150) lies on these lines: 1,147   2,101   4,152   7,80   20,103   69,668   85,355   295,334   348,944   664,952

X(150) = reflection of X(I) in X(J) for these (I,J): (20,103), (101,116), (152,4), (664,1565)
X(150) = anticomplementary conjugate of X(514)


X(151) = REFLECTION OF X(20) IN X(109)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (by + cz - ax)/a, where x : y : z = X(102)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(151) = X(102)-of-anticomplementary triangle

X(151) lies on these lines: 2,102   20,109   149,962   152,928

X(151) = reflection of X(I) in X(J) for these (I,J): (20,109), (102,117)
X(151) = anticomplementary conjugate of X(515)


X(152) = REFLECTION OF X(20) IN X(101)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (by + cz - ax)/a, where x : y : z = X(103)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(152) = X(103)-of-anticomplementary triangle

X(152) lies on these lines: 2,103   4,150   20,101   151,928

X(152) = reflection of X(I) in X(J) for these (I,J): (20,101), (103,118), (150,4)
X(152) = anticomplementary conjugate of X(516)


X(153) = REFLECTION OF X(20) IN X(100)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (by + cz - ax)/a, where x : y : z = X(104)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(153) = X(104)-of-anticomplementary triangle

X(153) lies on these lines: 2,104   4,145   7,80   11,388   20,100   515,908

X(153) = reflection of X(I) in X(J) for these (I,J): (20,100), (104,119), (149,4), (1320,1537)
X(153) = anticomplementary conjugate of X(517)


X(154) = X(3)-CEVA CONJUGATE OF X(6)

Trilinears       (cos A - cos B cos C)a2 : (cos B - cos C cos A)b2 : (cos C - cos A cos B)c2
                        = a(tan B + tan C - tan A) : b(tan C + tan A - tan B): c(tan A + tan B - tan C)

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin2 A)(tan B + tan C - tan A)

X(154) = X(2)-of-tangential triangle

X(154) lies on these lines:

3,64   6,25   22,110   26,155   31,56   48,55   160,418   197,692   198,212   205,220   237,682

X(154) is the {X(26),X(156)}-harmonic conjugate of X(155). For a list of harmonic conjugates of X(154), click Tables at the top of this page.

X(154) = isogonal conjugate of X(253)
X(154) = X(3)-Ceva conjugate of X(6)
X(154) = crosssum of X(I) and X(J) for these (I,J): (64,1073), (122,525)
X(154) = X(109)-beth conjugate of X(154)


X(155)  EIGENCENTER OF ORTHIC TRIANGLE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos A)[cos2B + cos2C - cos2A]
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A)f(A,B,C)

X(155) = X(4)-of-tangential-triangle. This point is also the center of the circle which cuts (extended) lines BC, CA, AB in pairs of points A' and A", B' and B", C' and C", respectively, such that angles A'AA", B'BB", C'CC" are all right angles. This is the Dou circle, described in

Jordi Dou, Problem 1140, Crux Mathematicorum, 28 (2002) 461-462.

Let A' be the isogonal conjugate of A with respect to the triangle BCX(4), and define B' and C' cyclically. Let A''B''C'' be the orthic triangle. Then the lines A'A'', B'B'', C'C'' concur in X(155). (Randy Hutson, 9/23/2011)

X(155) lies on these lines:
1,90   3,49   4,254   5,6   20,323   24,110   25,52   26,154   30,1498   159,511   195,381   382,399   450,1075   648,1093   651,1068

X(155) is the {X(26),X(156)}-harmonic conjugate of X(154). For a list of harmonic conjugates of X(155), click Tables at the top of this page.

X(155) = reflection of X(I) in X(J) for these (I,J): (3,1147), (26,156), (68,5)
X(155) = isogonal conjugate of X(254)
X(155) = eigencenter of cevian triangle of X(4)
X(155) = eigencenter of anticevian triangle of X(3)
X(155) = X(4)-Ceva conjugate of X(3)
X(155) = crosssum of X(136) and X(523)


X(156) = X(5)-OF-TANGENTIAL-TRIANGLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a[b2y/v + c2z/w - a2x/u],
                        u = u(A,B,C) = sin 2A, v = u(B,C,A), w = u(C,A,B);
                        x = x(A,B,C) = u2(v2 + w2) - (v2 - w2)2, y = x(B,C,A), z = x(C,A,B)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(156) = X(5)-of-tangential triangle

X(156) lies on these lines: 3,74   4,49   5,184   25,143   26,154   54,381   546,578   550,1092

X(156) is the {X(154),X(155)}-harmonic conjugate of X(26). For a list of harmonic conjugates, click Tables at the top of this page.

X(156) = midpoint of X(26) and X(155)


X(157) = X(6)-OF-TANGENTIAL-TRIANGLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a[b3cos B + c3cos C - a3cos A]
                        = g(a,b,c) : g(b,c,a) : g(c,a,b), where
                        g(a,b,c) = a[a6 - b6 - c6 - a4(b2 + c2) + b4(c2 + a2) + c4(a2 + b2)]

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(157) = X(6)-of-tangential triangle

X(157) lies on these lines: 3,66   6,248   22,183   25,53   161,418   206,216

X(157) = X(264)-Ceva conjugate of X(6)
X(157) = crosssum of X(127) and X(520)


X(158) = X(19)-CROSS CONJUGATE OF X(92)

Trilinears       sec2A : sec2B : sec2C
                        = 1/(1 + cos 2A) : 1/(1 + cos 2B) : 1/(1 + cos 2C)

Barycentrics  sec A tan A : sec B tan B : sec C tan C

X(158) lies on these lines:

1,29   3,243   4,65   10,318   37,281   46,412   47,162   75,240   107,759   225,1093   255,775   286,969   823,897   920,921

X(158) = isogonal conjugate of X(255)
X(158) = isotomic conjugate of X(326)
X(158) = X(I)-cross conjugate of X(J) for these (I,J): (19,92), (225,4)
X(158) = crosssum of X(520) and X(1364)
X(158) = crossdifference of every pair of points on line X(680)X(822)
X(158) = X(I)-aleph conjugate of X(J) for these (I,J): (821,158), (1105,255)
X(158) = X(107)-beth conjugate of X(34)


X(159) = X(9)-OF-TANGENTIAL-TRIANGLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = a[(a2 + b2 + c2)sin 2A + (c2 - b2 - a2)sin 2B + (b2 - c2 - a2)sin 2C]

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(159) = X(9)-of-tangential triangle

X(159) lies on these lines: 3,66   6,25   22,69   23,193   155,511   197,200

X(159) = reflection of X(I) in X(J) for these (I,J): (6,206), (66,141)
X(159) = X(I)-Ceva conjugate of X(J) for these (I,J): (22,3), (69,6)
X(159) = crosssum of X(127) and X(523)


X(160) = X(37)-OF-TANGENTIAL-TRIANGLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = a[(b2 + c2)sin 2A + (c2 - a2)sin 2B + (b2 - a2)sin 2C]

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(160) = X(37)-of-tangential triangle

X(160) lies on these lines: 3,66   6,237   22,325   95,327   154,418   206,57

X(160) = X(95)-Ceva conjugate of X(6)
X(160) = crosssum of X(338) and X(512)


X(161) = X(63)-OF-TANGENTIAL-TRIANGLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = a[(a2 + b2 + c2)sin2(2A) + (c2 - b2 - a2)sin2(2B) + (b2 - c2 - a2)sin2(2C)]

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(161) = X(63)-of-tangential triangle

X(161) lies on these lines: 6,25   22,343   26,68   157,418

X(161) = X(68)-Ceva conjugate of X(6)


X(162) = CEVAPOINT OF X(108) AND X(109)

Trilinears       1/(sin 2B - sin 2C) : 1/(sin 2C - sin 2A) : 1/(sin 2A - sin 2B)
                        = f(a,b,c) : f(b,c,a) : f(c,a,b) , where f(a,b,c) = 1/[(b2 - c2)(b2 + c2 - a2)]

Barycentrics  a/(sin 2B - sin 2C) : b/(sin 2C - sin 2A) : c/(sin 2A - sin 2B)

X(162) lies on these lines:
4,270   6,1013   19,897   27,673   28,88   29,58   31,92   47,158   63,204   100,112   107,109   108,110   190,643   238,415   240,896   242,422   255,1099   412,580   799,811

X(162) = isogonal conjugate of X(656)
X(162) = X(250)-Ceva conjugate of X(270)
X(162) = cevapoint of X(I) and X(J) for this (I,J): (108,109)
X(162) = X(I)-cross conjugate of X(J) for these (I,J): (108,107), (109,110)
X(162) = crosssum of X(810) and X(822)
X(162) = X(I)-aleph conjugate of X(J) for these (I,J): (28,1052), (107,920), (162,1), (648,63)
X(162) = trilinear pole of line X(1)X(19)
X(162) = trilinear product of X(1113) and X(1114)


X(163) = TRILINEAR PRODUCT X(6)*X(110)

Trilinears       (sin 2A)/(sin 2B - sin 2C) : (sin 2B)/(sin 2C - sin 2A) : (sin 2C)/(sin 2A - sin 2B)
                        = a2/(b2 - c2) : b2/(c2 - a2) : c2/(a2 - b2)

Barycentrics  a3/(b2 - c2) : b3/(c2 - a2) : c3/(a2 - b2)

X(163) lies on these lines: 1,293   19,563   31,923   32,849   48,1094   99,825   101,110   109,112   284,909   643,1018   692,906   798,1101   813,827

X(163) = crosssum of X(656) and X(661)
X(163) = X(I)-aleph conjugate of X(J) for these (I,J): (648,19), (662,610)


X(164)  INCENTER OF EXCENTRAL TRIANGLE

Trilinears       sin B/2 + sin C/2 - sin A/2 : sin C/2 + sin A/2 - sin B/2 : sin A/2 + sin B/2 - sin C/2
Barycentrics  a(sin B/2 + sin C/2 - sin A/2) : b(sin C/2 + sin A/2 - sin B/2) : c(sin A/2 + sin B/2 - sin C/2)

X(164) = X(1)-of-excentral triangle

X(164) lies on these lines: 1,258   9,168   40,188   57,177   165,167   173,504   361,503   362,845

X(164) = isogonal conjugate of X(505)
X(164) = X(188)-Ceva conjugate of X(1)
X(164) = X(I)-aleph conjugate of X(J) for these (I,J): (1,361), (2,362), (9,844), (188,164), (366,173)


X(165) = CENTROID OF THE EXCENTRAL TRIANGLE

Trilinears       tan(B/2) + tan(C/2) - tan(A/2) : tan(C/2) + tan(A/2) - tan(B/2) : tan(A/2) + tan(B/2) - tan(C/2)
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 3a2 - 2a(b + c) - (b - c)2

Barycentrics  a[tan(B/2) + tan(C/2) - tan(A/2)] : b[tan(C/2) + tan(A/2) - tan(B/2)] : c[tan(A/2) + tan(B/2) - tan(C/2)]

X(165) = centroid of the triangle with vertices X(1), X(8), X(20)
X(165) = centroid of the triangle with vertices X(4), X(20), X(40)

If DEF is the pedal triangle of X(165), then |AE| + |AF| = |BF| + |BD| = |CD| + |CE|. (Seiichi Kirikami, October 8, 2010.)

If you have The Geometer's Sketchpad, you can view X(165).

X(165) lies on these lines:
1,3   2,516   4,1698   9,910   10,20   32,1571   42,991   43,573   63,100   71,610   105,1054   108,1767   109,212   164,167   166,168   191,1079   210,971   218,1190   220,1615   227,1394   255,1103   269,1253   355,550   371,1703   372,1702   376,515   380,579   386,1695   411,936   479,1323   498,1770   572,1051   574,1572   580,601   612,990   614,902   631,946   750,968   846,1719   950,1788   958,1706   962,1125   1011,1730   1342,1701   1343,1700

X(165) is the {X(3),X(40)}-harmonic conjugate of X(1). For a list of harmonic conjugates of X(165), click Tables at the top of this page.

X(165) = isogonal conjugate of X(3062)
X(165) = X(9)-Ceva conjugate of X(1)
X(165) = X(I)-aleph conjugate of X(J) for these (I,J):
(2,169), (9,165), (21,572), (100,101), (188,9), (259,43), (365,978), (366,57), (650,1053)

X(165) = X(I)-beth conjugate of X(J) for these (I,J): (100,165), (643,200)


X(166)  GERGONNE POINT OF EXCENTRAL TRIANGLE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (tan A/2)/(cos B/2 + cos C/2 - cos A/2) - (tan B/2)/(cos C/2 + cos A/2 - cos B/2) - (tan C/2)/(cos A/2 + cos B/2 - cos C/2)

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A)f(A,B,C)

X(166) = X(7)-of-excentral triangle

X(166) lies on these lines: 1,1488   165,168   167,188

X(166) = X(266)-cross conjugate of X(57)
X(166) = cevapoint of X(266) and X(289)


X(167)  NAGEL POINT OF EXCENTRAL TRIANGLE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = s(B,C,A)t(B,C,A) + s(C,A,B)t(C,A,B) - s(A,B,C)t(A,B,C),
                        where s(A,B,C) = sin(A/2) and t(A,B,C) = (cos B/2 + cos C/2 - cos A/2) sec A/2

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A)f(A,B,C)

X(167) = X(8)-of-excentral triangle

X(167) lies on these lines: 1,174   164,165   166,188

X(167) = X(9)-aleph conjugate of X(166)


X(168)  MITTENPUNKT OF EXCENTRAL TRIANGLE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = sin A - sin B - sin C + 2[cos A/2 + sin(B/2 - A/2) + sin(C/2 - A/2)]

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A)f(A,B,C)

X(168) = X(9)-of-excentral triangle
X(168) is the homothetic center of the excentral and outer Hutson triangles; see X(363).

X(168) lies on these lines: 1,173   9,164   165,166

X(168) = X(188)-aleph conjugate of X(363)


X(169) = X(85)-CEVA CONJUGATE OF X(1)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = - (sin A)cos2(A/2) + (sin B)cos2(B/2) + (sin C)cos2(C/2)

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A)f(A,B,C)

X(169) = X(32)-of-excentral triangle.

X(169) lies on these lines: 1,41   3,910   4,9   6,942   46,672   57,277   63,379   65,218   220,517   572,610

X(169) = X(85)-Ceva conjugate of X(1)
X(169) = crosssum of X(6) and X(1473)

X(169) = X(I)-aleph conjugate of X(J) for these (I,J):
(2,165), (85,169), (86,572), (174,43), (188,170), (508,1), (514,1053), (664,101)


X(170) = X(9)-ALEPH CONJUGATE OF X(9)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = - (tan A/2)sec2(A/2) + (tan B/2)sec2(B/2) + (tan C/2)sec2(C/2)

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A)f(A,B,C)

X(170) = X(76)-of-excentral triangle

X(170) lies on these lines: 1,7   43,218

X(170) = X(220)-Ceva conjugate of X(1)
X(170) = X(I)-aleph conjugate of X(J) for these (I,J): (9,9), (55,43), (188,169), (220,170), (644,1018)
X(170) = X(664)-beth conjugate of X(170)


X(171) = {X(2), X(31)}-HARMONIC CONJUGATE OF X(238)

Trilinears       a2 + bc : b2 + ca : c2 + ab
Barycentrics  a3 + abc : b3 + abc : c3 + abc

X(171) lies on these lines: 1,3   2,31   4,601   6,43   7,983   10,58   37,846   42,81   47,498   63,612   72,1046   84,989   98,109   181,511   222,611   292,893   319,757   385,894   388,603   474,978   595,1125   602,631   756,896

X(171) = isogonal conjugate of X(256)
X(171) = X(292)-Ceva conjugate of X(238)
X(171) = X(I)-beth conjugate of X(J) for these (I,J): (100,171), (643,42)


X(172) = TRILINEAR PRODUCT X(6)*X(171)

Trilinears       a3 + abc : b3 + abc : c3 + abc
Barycentrics  a4 + bca2 : b4 + cab2 : c4 + abc2

X(172) lies on these lines:
1,32   6,41   12,230   21,37   35,187   36,39   42,199   58,101   65,248   350,384   577,1038   694,904   699,932

X(172) = isogonal conjugate of X(257)
X(172) = crossdifference of every pair of points on line X(522)X(1491)
X(172) = X(101)-beth conjugate of X(172)


X(173) = CONGRUENT ISOSCELIZERS POINT

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = cos B/2 + cos C/2 - cos A/2
Trilinears       tan(A/2) + sec(A/2) : tan(B/2) + sec(B/2) : tan(C/2) + sec(C/2)     (M. Iliev, 4/12/07)

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A)f(A,B,C)

Let P(B)Q(C) be an isoscelizer: let P(B) on sideline AC and Q(C) on AB be equidistant from A, so that AP(B)Q(C) is an isosceles triangle. The lines

P(B)-to-Q(C),       P(C)-to-Q(A),       P(A)-to-Q(B)

concur in X(173). (P. Yff, unpublished notes, 1989)

The intouch triangle of the intouch triangle of triangle ABC is perspective to triangle ABC, and X(173) is the perspector. (Eric Danneels, Hyacinthos 7892, 9/13/03)

Also, X(173) = X(1486)-of-the-intouch-triangle. (Darij Grinberg; see notes at X(1485) and X(1486).)

If you have The Geometer's Sketchpad, you can view Congruent Isoscelizers Point.

X(173) lies on these lines: 1,168   9,177   57,174   164,504   180,483   503,844   505,1130

X(173) = isogonal conjugate of X(258)
X(173) = X(174)-Ceva conjugate of X(1)

X(173) = X(I)-aleph conjugate of X(J) for these (I,J):
(1,503), (2,504), (174,173), (188,845), (366,164), (507,1), (508,362), (509,361)


X(174) = YFF CENTER OF CONGRUENCE

Trilinears       sec A/2 : sec B/2 : sec C/2
                         = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [bc/(b + c - a)]1/2

Barycentrics  sin A/2 : sin B/2 : sin C/2

In notes dated 1987, Yff raises a question concerning certain triangles lying within ABC: can three isoscelizers (as defined in connection with X(173)),

P(B)Q(C),   P(C)Q(A),   P(A)Q(B)

be constructed so that the four triangles

P(A)Q(A)A,     P(B)Q(B)B,     P(C)Q(C)C,     ABC

are congruent? After proving that the answer is yes, Yff moves the three isoscelizers in such a way that the three outer triangles,

P(A)Q(A)A,   P(B)Q(B)B,   P(C)Q(C)C

stay congruent and the inner triangle, ABC, shrinks to X(174).

Let D be the point on side BC such that (angle BID) = (angle DIC), and likewise for point E on side CA and point F on side AB. The lines AD, BE, CF concur in X(174). [Seiichi Kirikami, Jan. 29, 2010]   Generalization: if I is replaced by an arbitrary point P = p : q : r (trilinears), then the lines AD, BE, CF concur in the point K(P) = f(p,q,r,A) : f(q,r,p,B) : f(r,p,q,C), where f(p,q,r,A) = (q2 + r2 + 2qr cos A)-1/2. Moreover, if P* is the inverse of P in the circumcircle, then K(P*) = K(P). [Peter Moses, Feb. 1, 2010, based on Seiichi Kirikami's construction of X(174)]

X(174) is the homothetic center of ABC and the extangents triangle of the intouch triangle. (Randy Hutson, 9/23/2011)

If you have The Geometer's Sketchpad, you can view Yff Center of Congruence (1) and Yff Center of Congruence (2) and Yff Center of Congruence (3).

X(174) lies on these lines: 1,167   2,236   7,234   57,173   175,483   176,1143   188,266   481,1127   558,1489

X(174) = isogonal conjugate of X(259)
X(174) = anticomplement of X(2090)
X(174) = X(508)-Ceva conjugate of X(188)
X(174) = cevapoint of X(I) and X(J) for these (I,J): (1,173), (259,266)
X(174) = X(I)-cross conjugate of X(J) for these (I,J): (1,1488), (177,7), (259,188)
X(174) = crosssum of X(1) and X(503)
X(174) = X(556)-beth conjugate of X(556)


X(175) = ISOPERIMETRIC POINT

Trilinears       -1 + sec A/2 cos B/2 cos C/2 : -1 + sec B/2 cos C/2 cos A/2 : -1 + sec C/2 cos A/2 cos B/2
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A)(-1 + sec A/2 cos B/2 cos C/2)
X(175) = 2s*X(1) - (r + 4R)*X(7)

The points X(175) and X(176) are discussed in an 1890 article by Emile Lemoine, accessible at Gallica. The article begins on page 111, and the two points are considered beginning on page 128.

A point X is defined as an isoperimetric point of triangle ABC if |XB| + |XC| + |BC| = |XC| + |XA| + |CA| = |XA| + |XB| + |AB|. Veldkamp established that X = X(175), uniquely, for some triangles ABC, but the conditions he gives are not correct. Hajja and Yff proved that the condition tan(A/2) + tan(B/2) + tan(C/2) < 2 is necessary and sufficient. See also X(176) and the 1st and 2nd Eppstein points, X(481), X(482).

In unpublished notes, Yff proved that X(175) is the center of the outer Soddy circle. His proof later appeared in the paper by Hajja and Yff cited below.

Every point on the Soddy line has barycentric coordinates of the form a + k/sa : b + k/sb : c + k/sc, where k is a symmetric function in a,b,c, and sa=(b+c-a)/2, sb=(c+a-b)/2, sc=(a+b-c)/2. Writing S for 4*area(ABC):

X(175) = 2a - S/sa : 2b - S/sb : 2c - S/sc
X(176) = 2a + S/sa : 2b + S/sb : 2c + S/sc
X(481) = a - S/sa : b - S/sb : c - S/sc
X(482) = a + S/sa : b + S/sb : c + S/sc
X(1371) = a + 2S/(3 sa) : b + 2S/(3 sb) : c + 2S/(3 sc)
X(1372) = a - 2S/(3 sa) : b - 2S/(3 sb) : c - 2S/(3 sc)
X(1373) = a + 2S/sa : b + 2S/sb : c + 2S/sc
X(1374) = a - 2S/sa : b - 2S/sb : c - 2S/sc

Clark Kimberling and R. W. Wagner, Problem E 3020 and Solution, American Mathematical Monthly 93 (1986) 650-652 [proposed 1983].

G. R. Veldkamp, "The isoperimetric point and the point(s) of equal detour," American Mathematical Monthly 92 (1985) 546-558.

Mowaffaq Majja and Peter Yff, "The isoperimetric point and the point(s) of equal detour in a triangle," Journal of Geometry 87 (2007) 76-82.

There are exactly two points P such that the incircles of the triangles PBC, PCA, PAB are pairwise tangent to one another; the two points are X(175) and X(176). There are exactly two points P such that the radical center of the incircles of PBC, PCA, PAB is P; the two points are X(175) and X(176). (Randy Hutson, 9/23/2011)

X(175) lies on these lines: 1,7   8,1270   174,483   226,1131   490,664   651,1335

X(175) = X(8)-Ceva conjugate of X(176)
X(175) = X(664)-beth conjugate of X(175)
X(175) = {X(1),X(7)}-harmonic conjugate of X(176)


X(176) = EQUAL DETOUR POINT

Trilinears       1 + sec A/2 cos B/2 cos C/2 : 1 + sec B/2 cos C/2 cos A/2 : 1 + sec C/2 cos A/2 cos B/2
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A)(1 + sec A/2 cos B/2 cos C/2)
X(176) = 2s*X(1) + (r + 4R)*X(7)

The points X(175) and X(176) are discussed in an 1890 article by Emile Lemoine, accessible at Gallica. The article begins on page 111, and the two points are considered beginning on page 128.

The following construction was found by Elkies: call two circles within ABC companion circles if they are the incircles of two triangles formed by dividing ABC into two smaller triangles by passing a line through one of the vertices and some point on the opposite side; chain of circles O(1), O(2), ... such that O(n),O(n+1) are companion incircles for every n consists of at most six distinct circles; there is a unique chain consisting of only three distinct circles; and for this chain, the three subdividing lines concur in X(176).

A point X is defined as a point of equal detour of triangle ABC if |XB| + |XC| - |BC| = |XC| + |XA| - |CA| = |XA| + |XB| - |AB|. Veldkamp established that X = X(176) for some triangles ABC, but the conditions he gives are not correct. Hajja and Yff proved that the condition tan(A/2) + tan(B/2) + tan(C/2) < 2 is necessary and sufficient for the existence of exactly two points of equal detour and that the condition tan(A/2) + tan(B/2) + tan(C/2) = 2 is necessary and sufficient for the existence of exactly one point of equal detour. Yff found that X(176) is also is the center of the inner Soddy circle. See also X(175) and the 1st and 2nd Eppstein points, X(481), X(482).

G. R. Veldkamp, "The isoperimetric point and the point(s) of equal detour," American Mathematical Monthly 92 (1985) 546-558.

Noam D. Elkies and Jiro Fukuta, Problem E 3236 and Solution, American Mathematical Monthly 97 (1990) 529-531 [proposed 1987].

Mowaffaq Majja and Peter Yff, "The isoperimetric point and the point(s) of equal detour in a triangle," Journal of Geometry 87 (2007) 76-82.

There are exactly two points P such that the incircles of the triangles PBC, PCA, PAB are pairwise tangent to one another; the two points are X(175) and X(176). There are exactly two points P such that the radical center of the incircles of PBC, PCA, PAB is P; the two points are X(175) and X(176). For a point Q, let A' be the incenter of triangle BCQ, and define B' and C' cyclically; then X(176) is the only point Q such that Q is the incenter of A'B'C'. (Randy Hutson, 9/23/2011)

X(176) lies on these lines: 1,7   8,1271   174,1143   226,1132   489,664   651,1124

X(176) = X(8)-Ceva conjugate of X(175)
X(176) = X(664)-beth conjugate of X(176)
X(176) = {X(1),X(7)}-harmonic conjugate of X(175)


X(177) = 1st MID-ARC POINT

Trilinears       (cos B/2 + cos C/2) sec A/2 : (cos C/2 + cos A/2) sec B/2 : (cos A/2 + cos B/2) sec C/2
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A)(cos B/2 + cos C/2) sec A/2

Let A',B',C' be the first points of intersection of the angle bisectors of ABC with its incircle. The tangents at A', B', C' form a triangle A"B"C", and the lines AA",BB",CC" concur in X(177). Also, X(177) = X(1) of the intouch triangle.

Clark Kimberling and G. R. Veldkamp, Problem 1160 and Solution, Crux Mathematicorum 13 (1987) 298-299 [proposed 1986].

X(177) is the perspector of ABC and the Yff central triangle, and X(177) is X(65)-of-the-Yff-central-triangle . (Darij Grinberg, Hyacinthos #7689, 8/25/2003)

If you have The Geometer's Sketchpad, you can view X(177) and Yff Central Triangle.

X(177) lies on these lines: 1,167   7,555   8,556   9,173   57,164

X(177) = isogonal conjugate of X(260)
X(177) = X(7)-Ceva conjugate of X(234)
X(177) = crosspoint of X(7) and X(174)
X(177) = crosssum of X(55) and X(259)


X(178) = 2nd MID-ARC POINT

Trilinears       (cos B/2 + cos C/2) csc A : (cos C/2 + cos A/2) csc B : (cos A/2 + cos B/2) csc C
Barycentrics  cos B/2 + cos C/2 : cos C/2 + cos A/2 : cos A/2 + cos B/2

Let A',B',C' be the first points of intersection of the angle bisectors of ABC with its incircle. Let A",B",C" be the midpoints of segments BC,CA,AB, respectively. The lines A'A",B'B",C'C" concur in X(178).

Clark Kimberling, Problem 804, Nieuw Archikef voor Wiskunde 6 (1988) 170.

X(178) lies on these lines: 2,188   8,236

X(178) = complement of X(188)
X(178) = crosspoint of X(2) and X(508)


X(179) = 1st AJIMA-MALFATTI POINT

Trilinears       sec4(A/4) : sec4(B/4) : sec4(C/4)
Barycentrics  sin A sec4(A/4) : sin B sec4(B/4) : sin C sec4(C/4)

The famous Malfatti Problem is to construct three circles O(A), O(B), O(C) inside ABC such that each is externally tangent to the other two, O(A) is tangent to lines AB and AC, O(B) is tangent to BC and BA, and O(C) is tangent to CA and CB. Let A' = O(B)∩O(C), B' = O(C)∩O(A), C' = O(A)∩O(B). The lines AA',BB',CC' concur in X(179). Trilinears are found in Yff's unpublished notes. See also the Yff-Malfatti Point, X(400), having trilinears csc4(A/4) : csc4(B/4) : csc4(C/4), and the references for historical notes.

H. Fukagawa and D. Pedoe, Japanese Temple Geometry Problems (San Gaku), The Charles Babbage Research Centre, Winnipeg, Canada, 1989.

Michael Goldberg, "On the original Malfatti problem," Mathematics Magazine, 40 (1967) 241-247.

Clark Kimberling and I. G. MacDonald, Problem E 3251 and Solution, American Mathematical Monthly 97 (1990) 612-613.

If you have The Geometer's Sketchpad, you can view X(179).

X(179) lies on this line: 1,1142


X(180) = 2nd AJIMA-MALFATTI POINT

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/t(B,C,A) + 1/t(C,B,A) - 1/t(A,C,B),
                        t(A,B,C) = 1 + 2(sec A/4 cos B/4 cos C/4)2

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A)f(A,B,C)

Let A",B",C" be the excenters of ABC, and let A',B',C' be as in the construction of X(179). The lines A'A",B'B",B'B" concur in X(180). Trilinears are found in Yff's unpublished notes. See X(179).

If you have The Geometer's Sketchpad, you can view X(180) and X(180) External.

X(180) lies on this line: 173,483


X(181) = APOLLONIUS POINT

Trilinears       a(b + c)2/(b + c - a) : b(c + a)2/(c + a - b) : c(a + b)2/(a + b - c)
                        = a2cos2(B/2 - C/2) : b2cos2(C/2 - A/2) : c2cos2(A/2 - B/2)

Trilinears        h(a,b,c) : h(b,c,a) : h(c,a,b), where h(a,b,c) = [r cos(A/2) + s sin(A/2)]2, s = semiperimeter, r = inradius

Barycentrics  a3cos2(B/2 - C/2) : b3cos2(C/2 - A/2) : c3cos2(A/2 - B/2)

Let O(A),O(B),O(C) be the excircles. Apollonius's Problem includes the construction of the circle O tangent to the three excircles and encompassing them. (The circle is called the Apollonius circle.) Let A' = O∩O(A), B'=O∩O(B), C'=O∩O(C). The lines AA',BB',CC' concur in X(181). Yff derived trilinears in 1992.

X(181) is the external center of similitude (or exsimilicenter) of the incircle and Apollonius circle. The internal center is X(1682). (Peter J. C. Moses, 8/22/2003)

X(181) is the isogonal conjugate of the isotomic conjugate of X(12); also, X(181) is the {X(I),X(J)}-harmonic conjugate of X(K) for these (I,J,K): (31,51,3271), (42,1400,1402), (57,1401,1357), (57,1469,1401). (Peter J. C. Moses, 6/20/2014)

A proof of the the concurrence of lines AA',BB',CC' follows.
        A = exsimilicenter(incircle, A-excircle)
        A' = exsimilicenter(A-excircle, Apollonius circle)
        Let J = exsimilicenter(incircle, Apollonius circle).
By Monge's theorem, the points A, A', J are collinear. In particular, J lies on line AA', and cyclically, J lies on lines BB' and CC'. Therefore, J = X(181). (Darij Grinberg, Hyacinthos, 7461, 8/10/03)

See also

Clark Kimberling, Shiko Iwata, and Hidetosi Fukagawa, Problem 1091 and Solution, Crux Mathematicorum 13 (1987) 128-129; 217-218. [proposed 1985].

X(181) lies on these lines:
{1,970},{6,197},{8,959},{10,12},{11,2051},{25,2175},{31,51},{33,3022},{42,228},{43,57},{44,375},{55,573},{56,386},{58,1324},{81,5061},{171,511},{182,5329},{200,3779},{213,2333},{373,748},{389,3072},{518,3687},{553,1463},{575,5363},{612,3688},{750,3917},{756,2171},{942,5530},{994,1361},{1124,1685},{1254,1425},{1317,3032},{1335,1686},{1356,5213},{1358,3034},{1364,5348},{1376,4259},{1395,1843},{1672,1683},{1673,1684},{1674,1693},{1675,1694},{1695,1697},{2007,2019},{2008,2020},{2330,5285},{2534,2538},{2535,2539},{3027,3029},{3028,3031},{3056,5269},{3340,4517},{3781,5268},{3792,3819},{4276,5172}

X(181) = isogonal conjugate of X(261)
X(181) = X(I)-Ceva conjugate of X(J) for these (I,J): (12,2197), (59,4559), (65,2171), (2171,1500)
X(181) = X(I)-cross conjugate of X(J) for these (I,J): (872,1500), (2643,512)
X(181) = crosspoint of X(I) and X(J) for these (I,J): (42,1824), (59,4559), (65,1400), (1354,2171)
X(181) = crosssum of X(I) and X(J) for these (I,J): (2,2975), (11,4560), (21,333), (81,4225), (86,1444), (1098,2185)
X(181) = crossdifference of X(3904) and X(3910)
X(181) = X(I)-beth conjugate of X(J) for these (I,J): (42,181), (660,181), (756,756)

X(181) = trilinear product of X(I) and X(J) for these {I,J}:
{1,181},{6,2171},{7,872},{10,1402},{12,31},{19,2197},{25,201},{33,1425},{34,3690},{37,1400},{42,65},{55,1254},{56,756},{57,1500},{59,2643},{71,1880},{73,1824},{109,4705},{115,2149},{210,1042},{213,226},{225,228},{227,2357},{349,2205},{512,4551},{594,604},{608,3949},{651,4079},{661,4559},{762,1412},{798,4552},{1020,3709},{1089,1397},{1110,1365},{1214,2333},{1334,1427},{1395,3695},{1409,1826},{1415,4024},{1426,2318},{1441,1918},{3063,4605},{3124,4564},{4017,4557}

X(181) = barycentric product of X(I) and X(J) for these {I,J}:
{{1,2171},{2,181},{4,2197},{6,12},{7,1500},{9,1254},{10,1400},{19,201},{34,3949},{37,65},{42,226},{56,594},{57,756},{59,115},{71,225},{72,1880},{73,1826},{85,872},{109,4024},{210,1427},{213,1441},{227,1903},{278,3690},{281,1425},{307,2333},{321,1402},{349,1918},{512,4552},{523,4559},{604,1089},{608,3695},{651,4705},{661,4551},{663,4605},{664,4079},{762,1014},{1018,4017},{1020,4041},{1042,2321},{1091,2150},{1109,2149},{1214,1824},{1252,1365},{1262,4092},{1334,3668},{1404,4013},{1411,4053},{1415,4036},{1426,3694},{2222,2610},{2643,4564},{3124,4998},{3709,4566}

X(181) = X(I)-isoconjugate of X(J) for these (I,J):
(1,261),(2,2185),(7,1098),(8,757),(9,1509),(21,86),(27,1812),(28,332),(29,1444),(55,873),(58,314),(60,75),(69,270),(76,2150),(81,333),(99,3737),(200,552),(249,4858),(274,284),(283,286),(304,2189),(310,2194),(312,593),(348,2326),(514,4612),(645,1019),(649,4631),(650,4610),(662,4560),(663,4623),(693,4636),(763,2321),(849,3596),(1014,1043),(1021,4573),(1434,2287),(2170,4590),(4391,4556)


X(182) = MIDPOINT OF BROCARD DIAMETER

Trilinears       cos(A - ω) : cos(B - ω) : cos(C - ω)
                        = cos A + sin A tan ω : cos B + sin B tan ω : cos C + sin C tan ω
                        = sin A - sin(A - 2ω) : sin B - sin(B - 2ω) : sin C - sin(C - 2ω)
                        = cos A + cos(A - 2ω) : cos B + cos(B - 2ω) : cos C + cos(C - 2ω) (cf., X(39))

Barycentrics  sin A cos(A - ω) : sin B cos(B - ω) : sin C cos(C - ω)

X(182) = X(3) + X(6)

X(182) is the midpoint of the Brocard diameter (the segment X(3)-to-X(6)); also the center of the 1st Lemoine circle, and the center of the Brocard circle.

If you have The Geometer's Sketchpad, you can view X(1316), which includes X(182).

X(182) lies on these lines:
1,983   2,98   3,6   4,83   5,206   10,1678   22,51   24,1843   30,597   36,1469   40,1700   54,69   55,613   56,611   111,353   140,141   171,1397   373,1495   474,1437   517,1386   518,1385   524,549   692,1001   727,1293   729,1296   952,996

X(182) is the {X(371),X(372)}-harmonic conjugate of X(39). For a list of other harmonic conjugates of X(182), click Tables at the top of this page.

X(182) = midpoint of X(3) and X(6)
X(182) = reflection of X(I) in X(J) for these (I,J): (6,575), (141,140), (576,6)
X(182) = isogonal conjugate of X(262)
X(182) = isotomic conjugate of X(327)
X(182) = complement of X(1352)


X(183) = TRILINEAR PRODUCT X(75)X(182)

Trilinears       b2c2cos(A - ω) : c2a2cos(B - ω) : a2b2cos(C - ω)
Barycentrics  csc A cos(A - ω) : csc B cos(B - ω) : csc C cos(C - ω)
X(183) = 3*X(2) - 2(cos ω)2*X(6)

X(183) lies on these lines:
2,6   3,76   5,315   22,157   25,264   55,350   95,305   187,1003   274,474   316,381   317,427   383,621   538,574   622,1080   668,956

X(183) is the {X(2),X(69)}-harmonic conjugate of X(325). For a list of other harmonic conjugates of X(183), click Tables at the top of this page.

X(183) = isogonal conjugate of X(263)
X(183) = isotomic conjugate of X(262)
X(183) = X(645)-beth conjugate of X(183)


X(184) = INVERSE OF X(125) IN THE BROCARD CIRCLE

Trilinears       a2cos A : b2cos B : c2cos C
Barycentrics  a3cos A : b3cos B : c3cos C

X(184) is the homothetic center of triangles ABC and A'B'C', the latter defined as follows: let B1 and C1 be the points where the perpendicular bisector BC meets sidelines CA and AB, and cyclically define C2, A2; A3, B3. Then A'B'C' is formed by the perpendicular bisectors of segments B1C1, C2A2, A3B3. (Fred Lang, Hyacinthos #1190)

X(184) is the subject of Hyacinthos messages 5423-5441 (May, 2002). In #5423, Alexei Myakishev notes that X(184) serves as a common vertex of three triangles inside ABC, mutually congruent and similar to ABC. (The triangles can be labeled XBCCB, XCAAC, XABBA, with BC and CB on side BC, CA and AC on side CA, and AB and BA on side AB.) See

Alexei Myakishev, On the Procircumcenter and Related Points , Forum Geometricorum 3 (2003) 29-34.

In #5435, Paul Yiu cites Fred Lang's construction of X(184) and notes that the three triangles are then easily constructed from X(184). The triangles determine three other triangles with common vertex X(184); in #5437, Nikos Dergiades notes that the vertex angles of these are 4A - π, 4B - π, 4C - π, and that

X(184) = X(63)-of-the-orthic-triangle = X(226)-of-the-tangential-triangle
X(184) = homothetic center of the orthic triangle and the medial triangle of the tangential triangle.

Randy Hutson nots that X(184) is the exsimilicenter of the circumcircle and sine-triple-angle circle. (December 14, 2014)

X(184) lies on these lines:
2,98   3,49   4,54   5,156   6,25   23,576   24,389   26,52   22,511   31,604   32,211   48,212   55,215   157,570   160,571   199,573   205,213   251,263   351,686   381,567   397,463   398,462   418,577   572,1011   647,878

X(184) is the {X(6),X(25)}-harmonic conjugate of X(51). For a list of other harmonic conjugates of X(184), click Tables at the top of this page.

X(184) = isogonal conjugate of X(264)
X(184) = inverse-in-Brocard-circle of X(125)
X(184) = X(I)-Ceva conjugate of X(J) for these (I,J): (6,32), (54,6), (74,50)
X(184) = X(217)-cross conjugate of X(6)
X(184) = crosspoint of X(3) and X(6)

X(184) = crosssum of X(I) and X(J) for these (I,J): (2,4), (5,324), (6, 157), (92,318), (273,342), (338,523), (339,850), (427,1235), (491,492)

X(184) = crossdifference of every pair of points on line X(297)X(525)
X(184) = X(32)-Hirst inverse of X(237)
X(184) = X(I)-beth conjugate of X(J) for these (I,J): (212,212), (692,184)


X(185) = NAGEL POINT OF THE ORTHIC TRIANGLE

Trilinears       (cos A)[1 - cos A cos(B - C)] : (cos B)[1 - cos B cos(C - A)] : (cos C)[1 - cos C cos(A - B)]
Barycentrics  (sin 2A)[1 - cos A cos(B - C)] : (sin 2B)[1 - cos B cos(C - A)] : (sin 2C)[1 - cos C cos(A - B)]

Alexei Myakishev has noted that X(185) is the Nagel point of the orthic triangle only is ABC is an acute triangle.

X(185) lies on these lines:
1,296   3,49   4,51   5,113   6,64   20,193   25,1498   30,52   39,217   54,74   72,916   287,384   378,578   382,568   411,970   648,1105

X(185) = reflection of X(I) in X(J) for these (I,J): (4,389), (125,974)
X(185) = isogonal conjugate of X(1105)
X(185) = X(I)-Ceva conjugate of X(J) for these (I,J): (3,417), (4,235)
X(185) = crosspoint of X(3) and X(4)
X(185) = crosssum of X(I) and X(J) for these (I,J): (3,4), (25,1249)


X(186) = INVERSE-IN-CIRCUMCIRCLE OF X(4)

Trilinears       4 cos A - sec A : 4 cos B - sec B : 4 cos C - sec C
                        = sin 3A csc 2A : sin 3B csc 2B : sin 3C csc 2C

Barycentrics  (sin A)(4 cos A - sec A) : (sin B)(4 cos B - sec B) : (sin C)(4 cos C - sec C)

X(186) lies on these lines: 2,3   54,389   93,252   98,935   107,477   112,187   249,250

X(186) is the {X(3),X(24)}-harmonic conjugate of X(4). For a list of other harmonic conjugates of X(100), click Tables at the top of this page.

X(186) = reflection of X(I) in X(J) for these (I,J): (4,403), (403,468)
X(186) = isogonal conjugate of X(265)
X(186) = isotomic conjugate of X(328)
X(186) = complement of X(3153)
X(186) = anticomplement of X(2072)
X(186) = inverse-in-circumcircle of X(4)
X(186) = X(340)-Ceva conjugate of X(323)
X(186) = X(50)-cross conjugate of X(323)
X(186) = crosspoint of X(54) and X(74)
X(186) = crosssum of X(I) and X(J) for these (I,J): (5,30), (621,622)
X(186) = crossdifference of every pair of points on line X(216)X(647)


X(187) = INVERSE-IN-CIRCUMCIRCLE OF X(6) (SCHOUTE CENTER)

Trilinears       a(2a2 - b2 - c2) : b(2b2 - c2 - a2) : c(2c2 - a2 - b2)
                        =sin A - 3 cos A tan ω : sin B - 3 cos B tan ω : sin C - 3 cos C tan ω (Peter J. C. Moses, 8/22/03)

Barycentrics  a2(2a2 - b2 - c2) : b2(2b2 - c2 - a2) : c2(2c2 - a2 - b2)

Let L denote the line having trilinears of X(187) as coefficients. Then L is the line passing through X(2) perpendicular to the Euler line.

X(187) is the inverse in the van Lamoen circle of X(2) (Randy Hutson, 9/23/2011)

If you have The Geometer's Sketchpad, you can view X(1316), which includes X(187).

X(187) lies on these lines:
2,316   3,6   23,111   30,115   35,172   36,1015   74,248   99,385   110,352   112,186   183,1003   237,351   249,323   325,620   395,531   396,530   729,805

X(187) is the {X(3),X(6)}-harmonic conjugate of X(574). For a list of other harmonic conjugates of X(187), click Tables at the top of this page.

X(187) is the radical trace of the circumcircle and Brocard circle. (Peter J. C. Moses, 8/24/03)

X(187) = midpoint of X(I) and X(J) for these (I,J): (15,16), (99,385)
X(187) = reflection of X(I) in X(J) for these (I,J): (115,230), (316,625), (325,620)
X(187) = isogonal conjugate of X(671)
X(187) = inverse-in-circumcircle of X(6)
X(187) = inverse-in-Brocard-circle of X(574)
X(187) = complement of X(316)
X(187) = anticomplement of X(625)
X(187) = X(111)-Ceva conjugate of X(6)
X(187) = crosspoint of X(I) and X(J) for these (I,J): (2,67), (6,111), (468,524)
X(187) = crosssum of X(I) and X(J) for these (I,J): (2,524), (6,23), (111,895), (115,690)
X(187) = crossdifference of every pair of points on line X(2)X(523)
X(187) = X(55)-beth conjugate of X(187)


X(188) = 2nd MID-ARC POINT OF ANTICOMPLEMENTARY TRIANGLE

Trilinears       csc A/2 : csc B/2 : csc C/2
                        = [bc(b + c - a)]1/2 : [ca(c + a - b)]1/2 : [ab(a + b - c)]1/2

Barycentrics  cos A/2 : cos B/2 : cos C/2

Let A'B'C' be the excentral triangle of ABC, so that A' = -1 : 1 : 1 (trilinears). Let A'' be the point where the bisector of angle BA'C meets the line BC. Define B'' and C'' cyclically. The lines AA'', BB'', CC'' concur in X(188). (Seiichi Kirikami, February 14, 2010)

X(188) lies on these lines: 1,361   2,178   9,173   40,164   166,167   174,266

X(188) = isogonal conjugate of X(266)
X(188) = isotomic conjugate of X(4146)
X(188) = anticomplement of X(178)
X(188) = X(2)-Ceva conjugate of X(236)
X(188) = cevapoint of X(1) and X(164)
X(188) = X(259)-cross conjugate of X(174)
X(188) = crosssum of X(1) and X(361)
X(188) = X(188)-beth conjugate of X(266)


X(189) = CYCLOCEVIAN CONJUGATE OF X(8)

Trilinears       bc/(cos B + cos C - cos A - 1) : ca/(cos C + cos A - cos B - 1) : ab/(cos A + cos B - cos C - 1)
Barycentrics  1/(cos B + cos C - cos A - 1) : 1/(cos C + cos A - cos B - 1) : 1/(cos A + cos B - cos C - 1)

X(189) is the perspector of triangle ABC and the pedal triangle of X(84).

X(189) lies on these lines: 2,77   7,92   8,20   29,81   69,309   222,281

X(189) = isogonal conjugate of X(198)
X(189) = isotomic conjugate of X(329)
X(189) = cyclocevian conjugate of X(8)
X(189) = anticomplement of X(223)
X(189) = X(309)-Ceva conjugate of X(280)
X(189) = cevapoint of X(84) and X(282)
X(189) = X(I)-cross conjugate of X(J) for these (I,J): (4,7), (57,2), (282,280)


X(190) = YFF PARABOLIC POINT

Trilinears       bc/(b - c) : ca/(c - a) : ab/(a - b)
Barycentrics  1/(b - c) : 1/(c - a) : 1/(a - b)

In unpublished notes, Yff has studied the parabola tangent to sidelines BC, CA, AB and having focus X(101). If A',B',C' are the respective points of tangency, then the lines AA', BB', CC' concur in X(190).

The line X(100)X(190) is tangent to the Steiner circumellipse at X(190) and to the circumcircle at X(100). (Peter Moses, July 7, 2009)

If you have The Geometer's Sketchpad, you can view X(190).

X(190) lies on the Steiner circumellipse and these lines:
1,537   2,45   6,192   7,344   8,528   9,75   10,671   37,86   40,341   44,239   63,312   69,144   71,290   72,1043   99,101   100,659   110,835   162,643   191,1089   238,726   320,527   321,333   329,345   350,672   513,660   514,1016   522,666   644,651   646,668   649,889   658,1020   670,799   789,813   872,1045   1222, 3057

X(190) = reflection of X(I) in X(J) for these (I,J): (239,44), (335,37), (673,9), (903,2)
X(190) = isogonal conjugate of X(649)
X(190) = isotomic conjugate of X(514)
X(190) = anticomplement of X(1086)
X(190) = X(I)-Ceva conjugate of X(J) for these (I,J): (99,100), (666,3570)
X(190) = cevapoint of X(I) and X(J) for these (I,J): (2,514), (9,522), (37,513), (440,525)
X(190) = X(I)-cross conjugate of X(J) for these (I,J): (513,86), (514,2), (522,75)
X(190) = crosssum of X(512) and X(798)
X(190) = X(I)-aleph conjugate of X(J) for these (I,J): (2,1052), (190,1), (645,411), (668,63), (1016,100)
X(190) = X(I)-beth conjugate of X(J) for these (I,J): (9,292), (190,651), (333,88), (645,190), (646,646), (1016,190)
X(190) = trilinear pole of the line X(1)X(2)



leftri Centers 191- 236 rightri
are Ceva conjugates. The P-Ceva conjugate of Q is the perspector
of the cevian triangle of P and the anticevian triangle of Q.

underbar

X(191) = X(10)-CEVA CONJUGATE OF X(1)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (b + c - a)(bc + ca + ab) + b3 + c3 - a3
Trilinears        SA + rR : SB + rR : SC + rR
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(191) = isogonal-conjugate-with-respect-to-excentral-triangle of X(3) (Randy Hutson, 9/23/2011)

X(191) lies on these lines:
1,21   9,46   10,267   30,40   35,72   36,960   109,201   165,1079   190,1089   329,498

X(191) = reflection of X(I) in X(J) for these (I,J): (1,21), (79,442)
X(191) = isogonal conjugate of X(267)
X(191) = X(10)-Ceva conjugate of X(1)
X(191) = crosspoint of X(I) and X(J) for these (I,J): (10,502)
X(191) = crosssum of X(58) and X(501)
X(191) = X(I)-aleph conjugate of X(J) for these (I,J): (2,2), (8,20), (10,191), (37,1045), (188,3), (366,6)
X(191) = X(643)-beth conjugate of X(191)


X(192) = X(1)-CEVA CONJUGATE OF X(2)
(CONGRUENT PARALLELIANS POINT)

Trilinears       bc(ca + ab - bc) : ca(ab + bc - ca) : ab(bc + ca - ab)
Barycentrics  ca + ab - bc : ab + bc - ca : bc + ca - ab

Segments through X(192) parallel to the sidelines with endpoints on the sidelines have equal length. For references as early as 1881, see Hyacinthos message 2929 (Paul Yiu, May 29, 2001). See also

Sabrina Bier, "Equilateral Triangles Intercepted by Oriented Parallelians," Forum Geometricorum 1 (2001) 25-32.

X(192) lies on these lines:
1,87   2,37   6,190   7,335   8,256   9,239   55,385   69,742   144,145   315,746   869,1045

X(192) = reflection of X(I) in X(J) for these (I,J): (8,984), (75,37), (1278,75)
X(192) = isogonal conjugate of X(2162)
X(192) = isotomic conjugate of X(330)
X(192) = complement of X(1278)
X(192) = anticomplement of X(75)
X(192) = X(1)-Ceva conjugate of X(2)
X(192) = crosspoint of X(1) and X(43)
X(192) = crosssum of X(1) and X(87)
X(192) = X(9)-Hirst inverse of X(239)
X(192) = X(646)-beth conjugate of X(192)


X(193) = X(4)-CEVA CONJUGATE OF X(2)

Trilinears       (csc A)(cot B + cot C - cot A) : (csc B)(cot C + cot A - cot B) : (csc C)(cot A + cot B - cot C)
Trilinears        (SA - a2)/a : (SB - b2)/b : (SC - c2)/c
Barycentrics  cot B + cot C - cot A : cot C + cot A - cot B : cot A + cot B - cot C
                        = 3a2 - b2 - c2 : 3b2 - c2 - a2 : 3c2 - a2 - b2 (Milorad Stevanovic, 5/12/2003)

Let A' be the reflection of the midpoint of segment BC in X(6), and define B' and C' cyclically. The lines AA', BB', CC' concur in X(193). (Randy Hutson, 9/23/2011)

X(193) lies on these lines:
2,6   7,239   8,894   20,185   23,159   44,344   66,895   144,145   146,148   253,287   317,393   330,959   371,488   372,487   608,651

X(193) = reflection of X(I) in X(J) for these (I,J): (3,1353), (4,1351), (69,6), (1352,576)
X(193) = isotomic conjugate of X(2996)
X(193) = anticomplement of X(69)
X(193) = anticomplementary conjugate of X(1370)
X(193) = X(4)-Ceva conjugate of X(2)
X(193) = X(2)-Hirst inverse of X(230)
X(193) = X(I)-beth conjugate of X(J) for these (I,J): (645,193), (662,608)


X(194) = X(6)-CEVA CONJUGATE OF X(2)

Trilinears       bc[a2b2 + a2c2 - b2c2] : ca[b2c2 + b2a2 - c2a2] : ab[c2a2 + c2b2 - a2b2]
Barycentrics  a2b2 + a2c2 - b2c2 : b2c2 + b2a2 - c2a2 : c2a2 + c2b2 - a2b2
Barycentrics  cot2A - csc2A cos 2ω : cot2B - csc2B cos 2ω : cot2C - csc2C cos 2ω      (M. Iliev, 5/13/07)

X(194) lies on these lines:
{1,87},{2,39},{3,385},{4,147},{6,384},{8,730},{10,3097},{20,185},{32,99},{63,239},{69,695},{75,1107},{83,3734},{183,5013},{184,3492},{190,2176},{257,986},{262,2996},{263,3498},{304,3797},{315,736},{325,5025},{350,2275},{401,1993},{487,1587},{488,1588},{548,3793},{574,1078},{616,3104},{617,3105},{627,3106},{628,3107},{648,1968},{712,4393},{1007,2023},{1593,1941},{1654,4201},{1670,2547},{1671,2546},{1909,2276},{2128,2285},{3096,4045},{3212,3503},{3314,3933},{3413,3557},{3414,3558},{3522,5188},{3770,4261},{3906,5652},{3972,5007}

X(194) is the radical center of the Neuberg circles.

X(194) is the {X(39),X(76)}-harmonic conjugate of X(2). For a list of other harmonic conjugates of X(194), click Tables at the top of this page.

X(194) = reflection of X(76) in X(39)
X(194) = isogonal conjugate of X(3224)
X(194) = isotomic conjugate of X(2998)
X(194) = anticomplement of X(76)
X(194) = anticomplementary conjugate of X(315)
X(194) = eigencenter of cevian triangle of X(6)
X(194) = eigencenter of anticevian triangle of X(2)

X(194) = X(6)-Ceva conjugate of X(2)
X(194) = X(3)-Hirst inverse of X(385)


X(195) = X(5)-CEVA CONJUGATE OF X(3)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos A)(v + w - u),
                        u = u(A,B,C) = cos A cos(B - A) cos(C - A), v = u(B,C,A), w = u(C,A,B)

Barycentrics  af(A,B,C) : bf(B,C,A) : cf(C,A,B)
Barycentrics  4 cos 2A + cot2A - cot A cot ω : 4 cos 2B + cot2B - cot B cot ω : 4 cos 2C + cot2C - cot C cot ω      (M. Iliev, 5/13/07)

X(195) lies on the Napoleon cubic and these lines:
1,3467   3,54   4,399   5,3459   6,17   49,52   110,143   140,323   155,381   382,1498   2121,3462   3461,3468

X(195) = reflection of X(I) in X(J) for these (I,J): (3,54), (54,1493), (3519,1209)
X(195) = isogonal conjugate of X(3459)
X(195) = X(5)-Ceva conjugate of X(3)
X(195) = crosssum of X(137) and X(523)


X(196) = X(7)-CEVA CONJUGATE OF X(4)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos B + cos C - cos A - 1) sec A tan A/2
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (cos B + cos C - cos A - 1) tan A tan A/2

X(196) lies on these lines:
1,207   2,653   4,65   7,92   19,57   34,937   40,208   55,108   226,281   329,342

X(196) = isogonal conjugate of X(268)
X(196) = X(I)-Ceva conjugate of X(J) for these (I,J): (7,4), (92,278)
X(196) = cevapoint of X(19) and X(207)
X(196) = X(221)-cross conjugate of X(347)
X(196) = X(I)-beth conjugate of X(J) for these (I,J): (648,2) (653,196)


X(197) = X(8)-CEVA CONJUGATE OF X(6)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = a[-a2tan A/2 + b2tan B/2 + c2tan C/2]
Barycentrics  af(A,B,C) : bf(B,C,A) : cf(C,A,B)

X(197) lies on these lines:
3,10   6,181   19,25   22,100   42,48   56,227   159,200

X(197) = X(8)-Ceva conjugate of X(6)
X(197) = crosssum of X(124) and X(514)


X(198) = X(9)-CEVA CONJUGATE OF X(6)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = a(cos B + cos C - cos A - 1)
Barycentrics  af(A,B,C) : bf(B,C,A) : cf(C,A,B)

X(198) lies on these lines:
3,9   6,41   19,25   45,1030   64,71   100,346   101,102   154,212   208,227   218,579   284,859   478,577   958,966

X(198) = isogonal conjugate of X(189)
X(198) = X(I)-Ceva conjugate of X(J) for these (I,J): (3,55), (9,6), (223,221)
X(198) = crosspoint of X(40) and X(223)
X(198) = crosssum of X(I) and X(J) for these (I,J): (57,1422), (84,282), (513,1146), (650,1364), (1433,1436)
X(198) = crossdifference of every pair of points on line X(522)X(905)
X(198) = X(I)-beth conjugate of X(J) for these (I,J): (9,19), (101,198)


X(199) = X(10)-CEVA CONJUGATE OF X(6)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a[b4 + c4 - a4 + (b2 + c2 - a2)(bc + ca + ab)]
Barycentrics  af(A,B,C) : bf(B,C,A) : cf(C,A,B)

X(199) lies on these lines: 2,3   42,172   51,572   55,1030   184,573

X(199) = X(10)-Ceva conjugate of X(6)
X(199) = crosspoint of X(101) and X(250)
X(199) = crosssum of X(125) and X(514)


X(200) = X(8)-CEVA CONJUGATE OF X(9)

Trilinears       cot2(A/2) : cot2(B/2) : cot2(C/2)
                        = (b + c - a)2 : (c + a - b) 2 : (a + b - c)2
                        = (1 + cos A)/(1 - cos A) : (1 + cos B)/(1 - cos B) : (1 + cos C)/(1 - cos C) (Randy Hutson, 9/23/2011)

Barycentrics  a(b + c - a)2 : b(c + a - b) 2 : c(a + b - c)2

X(200) lies on these lines:
1,2   3,963   9,55   33,281   40,64   46,1004   57,518   63,100   69,269   159,197   219,282   220,728   255,271   318,1089   319,326   329,516   341,1043   756,968

X(200) is the {X(8),X(78)}-harmonic conjugate of X(1). For a list of harmonic conjugates of X(200), click Tables at the top of this page.

X(200) = reflection of X(I) in X(J) for these (I,J): (1,997), (57,1376)
X(200) = isogonal conjugate of X(269)
X(200) = isotomic conjugate of X(1088)
X(200) = X(8)-Ceva conjugate of X(9)
X(200) = cevapoint of X(220) and X(480)
X(200) = X(220)-cross conjugate of X(9)
X(200) = crosspoint of X(8) and X(346)
X(200) = crosssum of X(I) and X(J) for these (I,J): (56,1407), (57,1420), (1042,1427)
X(200) = X(I)-beth conjugate of X(J) for these (I,J): (100,223), (200,55), (643,165)


X(201) = X(10)-CEVA CONJUGATE OF X(12)

Trilinears       (cos A)[1 + cos(B - C)] : (cos B)[1 + cos(C - A)] : (cos C)[1 + cos(A - B)]
Barycentrics  (sin 2A)[1 + cos(B - C)] : (sin 2B)[1 + cos(C - A)] : (sin 2C)[1 + cos(A - B)]

X(201) lies on these lines:
1,212   9,34   10,225   12,756   33,40   37,65   38,56   55,774   57,975   63,603   72,73   109,191   210,227   220,221   255,1060   337,348   388,984   601,920

X(201) = isogonal conjugate of X(270)
X(201) = X(10)-Ceva conjugate of X(12)
X(201) = crosspoint of X(10) and X(72)
X(201) = crosssum of X(I) and X(J) for these (I,J): (1,580), (28,58)
X(201) = X(I)-beth conjugate of X(J) for these (I,J): (72,201), (1018,201)


X(202) = X(1)-CEVA CONJUGATE OF X(15)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = u(v + w - u),
                         u = u(A,B,C) = sin(A + π/3), v = u(B,C,A), w = u(C,A,B)

Trilinears       1 - cos(A + π/3) : 1 - cos(B + π/3) : 1 - cos(C + π/3)   (Joe Goggins, Oct. 19, 2005)

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(202) lies on these lines:
1,62   6,101   11,13   12,18   15,36   16,55   17,499   56,61   395,495   397,496

X(202) = X(1)-Ceva conjugate of X(15)


X(203) = X(1)-CEVA CONJUGATE OF X(16)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = u(v + w - u),
                         u = u(A,B,C) = sin(A - π/3), v = u(B,C,A), w = u(C,A,B)

Trilinears       1 + cos(A + 2π/3) : 1 + cos(B + 2π/3) : 1 + cos(C + 2π/3)   (Joe Goggins, Oct. 19, 2005)

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(203) lies on these lines:
1,61   6,101   11,14   12,17   15,55   16,36   18,499   56,62   396,495   398,496

X(203) = X(1)-Ceva conjugate of X(16)


X(204) = X(1)-CEVA CONJUGATE OF X(19)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (tan A)(tan B + tan C - tan A)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(204) lies on these lines: 6,33   19,31   25,34   55,1033   63,162   108,223   207,221

X(204) = X(1)-Ceva conjugate of X(19)
X(204) = X(I)-beth conjugate of X(J) for these (I,J): (108,204), (162,223)


X(205) = X(9)-CEVA CONJUGATE OF X(31)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a2[b2tan B/2 + c2tan C/2 - a2tan A/2]
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(205) lies on these lines: 25,41   37,48   78,101   154,220   184,213

X(205) = X(9)-Ceva conjugate of X(31)


X(206) = X(2)-CEVA CONJUGATE OF X(32)

Trilinears       a3(b4 + c4 - a4) : b3(c4 + a4 - b4) : c3(a4 + b4 - c4)
Barycentrics  a4(b4 + c4 - a4) : b4(c4 + a4 - b4) : c4(a4 + b4 - c4)

This is also X(66) of the medial triangle.

X(206) lies on these lines:
2,66   5,182   6,25   26,511   69,110   157,216   160,577   219,692   237,571

X(206) = midpoint of X(I) and X(J) for these (I,J): (6,159), (110,1177)
X(206) = complement of X(66)
X(206) = complementary conjugate of X(427)
X(206) = X(2)-Ceva conjugate of X(32)
X(206) = crosspoint of X(2) and X(315)
X(206) = crosssum of X(339) and X(523)


X(207) = X(1)-CEVA CONJUGATE OF X(34)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (1 - sec A)(sec B + sec C - sec A - 1)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(207) lies on these lines: 1,196   19,56   33,64   34,1042   40,108   78,653   204,221

X(207) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,34), (196,19)
X(207) = X(1)-beth conjugate of X(64)


X(208) = X(4)-CEVA CONJUGATE OF X(34)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (1 - sec A)(cos B + cos C - cos A - 1)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(208) lies on these lines:
1,102   4,57   19,225   25,34   33,64   40,196   198,227   226,406   318,653

X(208) = isogonal conjugate of X(271)
X(208) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,34), (57,19), (342,223)
X(208) = crosssum of X(3) and X(1433)
X(208) = X(I)-beth conjugate of X(J) for these (I,J): (108,208), (162,1)


X(209) = X(4)-CEVA CONJUGATE OF X(37)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (sin B + sin C)[sin A + sin(A - B) + sin(A - C)]
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(209) lies on these lines: 6,31   10,12   44,51   306,518

X(209) = isogonal conjugate of X(272)
X(209) = X(4)-Ceva conjugate of X(37)


X(210) = X(10)-CEVA CONJUGATE OF X(37)

Trilinears       (b + c)(b + c - a) : (c + a)(c + a - b) : (a + b)(a + b - c)
Barycentrics  a(b + c)(b + c - a) : b(c + a)(c + a - b) : c(a + b)(a + b - c)

X(210) lies on these lines:
2,354   6,612   8,312   9,55   10,12   31,44   33,220   37,42   38,899   43,984   45,968   51,374   56,936   63,1004   78,958   165,971   201,227   213,762   381,517   392,519   430,594   869,1107   956,997   976,1104

X(210) = X(2)-of-extouch triangle, so that X(210)X(1158) = Euler line of the extouch triangle

X(210) = reflection of X(I) in X(J) for these (I,J): (51,375), (354,2)
X(210) = isogonal conjugate of X(1014)
X(210) = X(10)-Ceva conjugate of X(37)
X(210) = crosspoint of X(8) and X(9)
X(210) = crosssum of X(I) and X(J) for these (I,J): (56,57), (58,1412)
X(210) = crossdifference of every pair of points on line X(1019)X(1429)
X(210) = X(I)-beth conjugate of X(J) for these (I,J): (200,210), (210,42)


X(211) = X(4)-CEVA CONJUGATE OF X(39)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C)
                        = sin(A + ω)[cos B sin(B + ω) + cos C sin(C + ω) - cos A sin(A + ω)]

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(211) lies on these lines: 5,141   32,184   52,114

X(211) = X(4)-Ceva conjugate of X(39)


X(212) = X(9)-CEVA CONJUGATE OF X(41)

Trilinears       (cos A)(1 + cos A) : (cos B)(1 + cos B) : (cos C)(1 + cos C)
                        = (cos A)cos2(A/2) : (cos B)cos2(B/2) : (cos C)cos2(C/2)
                        = a2(b + c - a)(b2 + c2 - a2) : b2(c + a - b)(c2 + a2 - b2) : c2(a + b - c)(a2 + b2 - c2)

Barycentrics  (sin 2A)(1 + cos A) : (sin 2B)(1 + cos B) : (sin 2C)(1 + cos C)

X(212) lies on these lines:
1,201   3,73   6,31   9,33   11,748   34,40   35,47   48,184   56,939   63,1040   78,283   109,165   154,198   238,497   312,643   582,942

X(212) = isogonal conjugate of X(273)
X(212) = X(I)-Ceva conjugate of X(J) for these (I,J): (3,48), (9,41), (283,219)
X(212) = X(228)-cross conjugate of X(55)
X(212) = crosspoint of X(I) and X(J) for these (I,J): (3,219), (9,78)
X(212) = crosssum of X(I) and X(J) for these (I,J): (4,278), (34,57)
X(212) = X(212)-beth conjugate of X(184)


X(213) = X(6)-CEVA CONJUGATE OF X(42)

Trilinears       (b + c)a2 : (c + a)b2 : (a + b)c2
Trilinears       a2(ar - S) : b2(br - S) : c2(cr - S)
Barycentrics  (b + c)a3 : (c + a)b3 : (a + b)c3

X(213) lies on these lines: 1,6   8,981   31,32   39,672   58,101   63,980   83,239   100,729   184,205   274,894   607,1096   667,875   692,923

X(213) = isogonal conjugate of X(274)
X(213) = X(I)-Ceva conjugate of X(J) for these (I,J): (6,42), (37,228)
X(213) = crosspoint of X(6) and X(31)
X(213) = crosssum of X(I) and X(J) for these (I,J): (2,75), (81,1444), (85,348)
X(213) = crossdifference of every pair of points on line X(320)X(350)
X(213) = X(I)-beth conjugate of X(J) for these (I,J): (41,213), (101,65), (644,213)


X(214) = X(2)-CEVA CONJUGATE OF X(44)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (b + c - 2a)(b2 + c2 - a2 - bc)
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(214) lies on these lines: 1,88   2,80   9,48   10,140   11,442   36,758   44,1017   119,515   142,528   535,908   662,759   1015,1100

X(214) = midpoint of X(1) and X(100)
X(214) = reflection of X(11) in X(1125)
X(214) = isogonal conjugate of X(1168)
X(214) = complement of X(80)
X(214) = X(2)-Ceva conjugate of X(44)
X(214) = crosspoint of X(2) and X(320)
X(214) = X(21)-beth conjugate of X(244)


X(215) = X(1)-CEVA CONJUGATE OF X(50)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (sin 3A)(sin 3B + sin 3C - sin 3A)
Trilinears       cos2(3A/2) : cos2(3B/2) : cos2(3C/2)     (M. Iliev, 4/12/07)
Trilinears       1 + cos 3A : 1 + cos 3B : 1+ cos 3C     (M. Iliev, 4/12/07)

X(215) is the insimilicenter of the incircle and the sine-triple-angle circle. (Randy Hutson, December 14, 2014)

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(215) lies on these lines: 1,49   11,110   12,54   55,184

X(215) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,50)


X(216) = X(5)-CEVA CONJUGATE OF X(51)

Trilinears       sin 2A cos(B - C) : sin 2B cos(C - A) : sin 2C cos(A - B)
Barycentrics  (sin A)(sin 2A)cos(B - C) : sin B sin 2B cos(C - A) : sin C sin 2C cos(A - B)

X(216) is the perspector of triangle ABCand the tangential triangle of the Johnson circumconic. (Randy Hutson, 9/23/2011)

X(216) lies on these lines:
2,232   3,6   5,53   51,418   95,648   97,288   115,131   157,206   373,852   395,465   396,466   631,1075   1015,1060

X(216) = isogonal conjugate of X(275)
X(216) = isotomic conjugate of X(276)
X(216) = inverse-in-Brocard-circle of X(577)
X(216) = complement of X(264)
X(216) = X(I)-Ceva conjugate of X(J) for these (I,J): (2,5), (3,418), (5,51), (324,52)
X(216) = cevapoint of X(217) and X(418)
X(216) = X(217)-cross conjugate of X(51)
X(216) = crosspoint of X(I) and X(J) for these (I,J): (2,3), (5,343)
X(216) = crosssum of X(4) and X(6)
X(216) = crossdifference of every pair of points on line X(186)X(523)


X(217) = X(6)-CEVA CONJUGATE OF X(51)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (sin3A) cos A cos(B - C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(217) lies on these lines: 4,6   32,184   39,185   54,112   83,287   232,389

X(217) = isogonal conjugate of X(276)
X(217) = X(I)-Ceva conjugate of X(J) for these (I,J): (6,51), (216,418)
X(217) = crosspoint of X(I) and X(J) for these (I,J): (6,184), (51,216)
X(217) = crosssum of X(I) and X(J) for these (I,J): (2,264), (95,275)
X(217) = crossdifference of every pair of points on line X(340)X(520)


X(218) = X(7)-CEVA CONJUGATE OF X(55)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = cos2(A/2) [cos4(B/2) + cos4(C/2) - cos4(A/2)]

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(218) lies on these lines:
1,6   3,41   4,294   7,277   32,906   43,170   46,910   56,101   65,169   145,644   198,579   222,241   279,651

X(218) = isogonal conjugate of X(277)
X(218) = eigencenter of cevian triangle of X(7)
X(218) = eigencenter of anticevian triangle of X(55)
X(218) = X(7)-Ceva conjugate of X(55)
X(218) = crosssum of X(650) and X(1086)
X(218) = X(644)-beth conjugate of X(218)


X(219) = X(8)-CEVA CONJUGATE OF X(55)

Trilinears       cos A cot A/2 : cos B cot B/2 : cos C cot C/2
                        = (sin A)/(1 - sec A) : (sin B)/(1 - sec B) : (sin C)/(1 - sec C)
                        = 1/(csc A - 2 csc 2A) : 1/(csc B - 2 csc 2B) : 1/(csc C - 2 csc 2C)
                        = a(b + c - a)(b2 + c2 - a2) : b(c + a - b)(c2 + a2 - b2) : c(a + b - c)(a2 + b2 - c2)

Barycentrics  sin 2A cot A/2 : sin 2B cot B/2 : sin 2C cot C/2

X(219) lies on these lines:
1,6   3,48   8,29   10,965   19,517   40,610   41,1036   55,284   56,579   63,77   101,102   144,347   200,282   206,692   255,268   278,329   332,345   346,644   572,947   577,906   604,672

X(219) = isogonal conjugate of X(278)
X(219) = isotomic conjugate of X(331)
X(219) = X(I)-Ceva conjugate of X(J) for these (I,J): (8,55), (63,3), (283,212)
X(219) = X(I)-cross conjugate of X(J) for these (I,J): (48,268), (71,9), (212,3)
X(219) = crosspoint of X(I) and X(J) for these (I,J): (8,345), (64,78)
X(219) = crosssum of X(I) and X(J) for these (I,J): (19,34), (56,608)
X(219) = X(I)-beth conjugate of X(J) for these (I,J): (101,478), (219,48), (644,219)


X(220) = X(9)-CEVA CONJUGATE OF X(55)

Trilinears       a(b + c - a)2 : b(c + a - b)2 : c(a + b - c)2
Trilinears       (1 + cos A)2/sin A : (1 + cos B)2/sin B : (1 + cos C)2/sin C     (M. Iliev, 4/12/07)

Barycentrics  a2(b + c - a)2 : b2(c + a - b)2 : c2(a + b - c)2

X(220) lies on these lines:
1,6   3,101   8,294   33,210   40,910   41,55   48,963   63,241   64,71   78,949   144,279   154,205   169,517   200,728   201,221   268,577   277,1086   281,594   329,948   346,1043

X(220) = isogonal conjugate of X(279)
X(220) = X(I)-Ceva conjugate of X(J) for these (I,J): (9,55), (200,480)
X(220) = cevapoint of X(1) and X(170)
X(220) = crosspoint of X(9) and X(200)
X(220) = crosssum of X(57) and X(269)
X(220) = crossdifference of every pair of points on line X(513)X(676)
X(220) = X(I)-beth conjugate of X(J) for these (I,J): (101,221), (220,41), (644,220), (728,728)


X(221) = X(1)-CEVA CONJUGATE OF X(56)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (sin2A/2)(cos B + cos C - cos A - 1)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(221) lies on these lines:
1,84   3,102   6,19   8,651   31,56   40,223   55,64   201,220   204,207   960,1038

X(221) = isogonal conjugate of X(280)
X(221) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,56), (222,6), (223,198)
X(221) = crosspoint of X(I) and X(J) for these (I,J): (1,40), (196,347)
X(221) = crosssum of X(1) and X(84)
X(221) = X(I)-beth conjugate of X(J) for these (I,J): (1,34), (40,40), (101,220), (109,221), (110,3)


X(222) = X(7)-CEVA CONJUGATE OF X(56)

Trilinears       cos A tan A/2 : cos B tan B/2 : cos C tan C/2
                        = 1/(csc A + 2 csc 2A) : 1/(csc B + 2 csc 2B) : 1/(csc A + 2 csc 2C)
                        = a(b2 + c2 - a2)/(b + c - a) : b(c2 + a2 - b2)/(c + a - b) : c(a2 + b2 - c2)/(a + b - c)

Barycentrics  a2/(1 + sec A) : b2/(1 + sec B) : c2/(1 + sec C)

X(222) lies on these lines:
1,84   2,651   3,73   6,57   7,27   33,971   34,942   46,227   55,103   56,58   63,77   72,1038   171,611   189,281   218,241   226,478   268,1073   581,1035   601,1066   613,982   912,1060   1355,1363

X(222) = isogonal conjugate of X(281)
X(222) = X(I)-Ceva conjugate of X(J) for these (I,J): (7,56), (77,3), (81,57)
X(222) = cevapoint of X(6) and X(221)
X(222) = X(I)-cross conjugate of X(J) for these (I,J): (48,3), (73,77)
X(222) = crosspoint of X(7) and X(348)
X(222) = crosssum of X(I) and X(J) for these (I,J): (55,607), (650,1146)

X(222) = X(I)-beth conjugate of X(J) for these (I,J):
(21,1012), (63,63), (110,222), (287,222), (648,222), (651,222), (662,2), (895,222)


X(223) = X(2)-CEVA CONJUGATE OF X(57)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (tan A/2)(cos B + cos C - cos A - 1)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(223) lies on the Thomson cubic and these lines:
1,4   2,77   3,1035   6,57   9,1073   40,221   56,937   63,651   108,204   109,165   312,664   329,347   380,608   580,603   936,1038   1249,3352   3341,3349   3351,3356

X(223) = isogonal conjugate of X(282)
X(223) = complement of X(189)
X(223) = X(I)-Ceva conjugate of X(J) for these (I,J): (2,57), (77,1), (342,208), (347,40)
X(223) = cevapoint of X(198) and X(221)
X(223) = X(I)-cross conjugate of X(J) for these (I,J): (198,40), (227,347)
X(223) = crosspoint of X(2) and X(329)
X(223) = crosssum of X(6) and X(1436)

X(223) = X(I)-aleph conjugate of X(J) for these (I,J):
(63,1079), (77,223), (81,580), (174,46), (651,109)

X(223) = X(I)-beth conjugate of X(J) for these (I,J):
(2,278), (100,200), (162,204), (329,329), (651,223), (662,63)


X(224) = X(7)-CEVA CONJUGATE OF X(63)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = [cot B cos2(B/2) + cot C cos2(C/2) - cot A cos2(A/2)]cot A

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(224) lies on these lines: 1,377   3,63   8,914   21,90   46,100   65,1004   908,1079
X(224) = X(7)-Ceva conjugate of X(63)


X(225) = X(4)-CEVA CONJUGATE OF X(65)

Trilinears       (sec A)(cos B + cos C) : (sec B)(cos C + cos A) : (sec C)(cos A + cos B)
Barycentrics  (tan A)(cos B + cos C) : (tan B)(cos C + cos A) : (tan C)(cos A + cos B)

X(225) lies on these lines:
1,4   3,1074   7,969   10,201   12,37   19,208   28,108   46,254   65,407   75,264   91,847   158,1093   377,1038   412,775   653,897

X(225) = isogonal conjugate of X(283)
X(225) = isotomic conjugate of X(332)
X(225) = X(4)-Ceva conjugate of X(65)
X(225) = X(407)-cross conjugate of X(4)
X(225) = crosspoint of X(I) and X(J) for these (I,J): (4,158), (273,278)
X(225) = crosssum of X(I) and X(J) for these (I,J): (3,255), (212,219)
X(225) = X(I)-beth conjugate of X(J) for these (I,J): (4,225), (10,227), (108,1042), (318,10)


X(226) = X(7)-CEVA CONJUGATE OF X(65)

Trilinears       (csc A)(cos B + cos C) : (csc B)(cos C + cos A) : (csc C)(cos A + cos B)
                        = bc(b + c)/(b + c - a) : ca(c + a)/(c + a - b) : ab(a + b)/(a + b - c)

Barycentrics  (b + c)/(b + c - a) : (c + a)/(c + a - b) : (a + b)/(a + b - c)

X(226) = X(63)-of-medial-triangle
X(226) is the homothetic center of the intouch triangle and the triangle formed by the lines of the external pairs of extouch points of the excircles. (Randy Hutson, 9/23/2011)

X(226) lies on these lines:
1,4   2,7   5,912   10,12   11,118   13,1082   14,554   27,284   29,951   35,79   36,1006   37,440   41,379   46,498   55,516   56,405   76,85   78,377   81,651   83,1429   86,1412   92,342   98,109   102,1065   175,1131   176,1132   196,281   208,406   222,478   228,851   262,982   273,469   306,321   429,1426   443,936   452,1420   474,1466   481,485   482,486   495,517   535,551   664,671   673,1174   748,1471   857,1446   975,1038   990,1040   1029,1442   1260,1376   1284,1402   1401,1463

X(226) = reflection of X(993) in X(1125)
X(226) = isogonal conjugate of X(284)
X(226) = isotomic conjugate of X(333)
X(226) = complement of X(63)
X(226) = X(I)-Ceva conjugate of X(J) for these (I,J): (7,65), (349,307)
X(226) = cevapoint of X(37) and X(65)
X(226) = X(I)-cross conjugate of X(J) for these (I,J): (37,10), (73,307)
X(226) = crosspoint of X(2) and X(92)
X(226) = crosssum of X(I) and X(J) for these (I,J): (6,48), (41,55)
X(226) = crossdifference of every pair of points on line X(652)X(663)
X(226) = X(I)-beth conjugate of X(J) for these (I,J): (2,226), (21,1064), (100,42), (190,226), (312,306), (321,321), (335,226), (835,226)


X(227) = X(10)-CEVA CONJUGATE OF X(65)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (b + c)(cos B + cos C - cos A - 1)tan A/2
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(227) lies on these lines:
12,37   34,55   40,221   42,65   46,222   56,197   198,208   201,210   322,347   607,910

X(227) = isogonal conjugate of X(285)
X(227) = X(10)-Ceva conjugate of X(65)
X(227) = crosspoint of X(223) and X(347)
X(227) = crosssum of X(84) and X(1433)
X(227) = X(I)-beth conjugate of X(J) for these (I,J): (10,225), (40,227), (100,72)


X(228) = X(3)-CEVA CONJUGATE OF X(71)

Trilinears       (sin 2A)(sin B + sin C) : (sin 2B)(sin C + sin A) : (sin 2C)(sin A + sin B)
Barycentrics  (sin A sin 2A)(sin B + sin C) : (sin B sin 2B)(sin C + sin A) : (sin C sin 2C)(sin A + sin B)

X(228) lies on these lines:
3,63   9,1011   12,407   19,25   28,943   31,32   35,846   42,181   48,184   73,408   98,100   226,851

X(228) = isogonal conjugate of X(286)
X(228) = X(I)-Ceva conjugate of X(J) for these (I,J): (3,71), (37,213), (55,42)
X(228) = crosspoint of X(I) and X(J) for these (I,J): (3,48), (37,72), (55,212), (71,73)
X(228) = crosssum of X(I) and X(J) for these (I,J): (4,92), (7,273), (27,29), (28,81)
X(228) = crossdifference of every pair of points on line X(693)X(905)
X(228) = X(212)-beth conjugate of X(228)


X(229) = X(7)-CEVA CONJUGATE OF X(81)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (v + w - u)/(b + c),
                         u = u(a,b,c) = a(b + c - a)/(b + c), v = u(b,c,a), w = u(c,a,b)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(229) lies on these lines: 1,267   21,36   28,60   58,244   65,110   593,1104

X(229) = midpoint of X(1) and X(267)
X(229) = X(7)-Ceva conjugate of X(81)


X(230) = X(2)-CEVA CONJUGATE OF X(114)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = bc[a2(2a2 - b2 - c2) + (b2 - c2)2]

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(230) is the midpoint of the center of the (equilateral) pedal triangles of X(15) and X(16).

X(230) lies on these lines:
2,6   5,32   12,172   25,53   30,115   39,140   50,858   111,476   112,403   231,232   393,459   427,571   538,620   549,574   625,754

X(230) = midpoint of X(I) and X(J) for these (I,J): (115,187), (325,385), (395,396)
X(230) = isogonal conjugate of X(2987)
X(230) = complement of X(325)
X(230) = X(I)-Ceva conjugate of X(J) for these (I,J): (2,114), (297,1503)
X(230) = crosspoint of X(2) and X(98)
X(230) = crosssum of X(6) and X(511)
X(230) = crossdifference of every pair of points on line X(3)X(512)
X(230) = X(2)-Hirst inverse of X(193)
X(230) = X(I)-beth conjugate of X(J) for these (I,J): (281,230), (645,230)


X(231) = X(2)-CEVA CONJUGATE OF X(128)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = u(-au + bv + cw), u : v : w = X(128)
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(231) lies on these lines: 4,96   6,17   50,115   230,232

X(231) = complement of X(1273)
X(231) = X(2)-Ceva conjugate of X(128)
X(231) = crosssum of X(6) and X(1154)
X(231) = crossdifference of every pair of points on line X(3)X(1510)
X(231) = X(281)-beth conjugate of X(230)


X(232) = X(2)-CEVA CONJUGATE OF X(132)

Trilinears       tan A cos(A + ω) : tan B cos(B + ω) : tan C cos(C + ω)
Barycentrics  sin A tan A cos(A + ω) : sin B tan B cos(B + ω) : sin C tan C cos(C + ω)

X(232) lies on these lines:
{2,216}, {3,1968}, {4,39}, {6,25}, {19,444}, {22,577}, {23,250}, {24,32}, {33,2276}, {34,2275}, {50,3447}, {53,427}, {111,1304}, {112,186}, {115,403}, {132,1513}, {217,389}, {230,231}, {235,5254}, {297,325}, {378,574}, {385,648}, {406,5283}, {420,3229}, {428,5421}, {511,2211}, {566,5094}, {571,1485}, {800,1196}, {1015,1870}, {1033,1611}, {1172,2092}, {1180,3087}, {1235,3934}, {1506,1594}, {1560,3258}, {1575,1861}, {1593,5013}, {1597,5024}, {1609,3162}, {1692,2065}, {1783,5291}, {1995,5158}, {2971,5140}, {3053,3172}, {3089,5286}, {3269,3331}, {3518,5007}, {3542,3767}, {4220,5317}, {4232,5304}

X(232) = midpoint of X(3269) annd X(3331)
X(232) = isogonal conjugate of X(287)
X(232) = X(I)-Ceva conjugate of X(J) for these (I,J): (2,132), (297,511)
X(232) = X(237)-cross conjugate of X(511)
X(232) = crosssum of X(2) and X(401)
X(232) = crossdifference of every pair of points on line X(3)X(525)
X(232) = orthojoin of X(132)
X(232) = X(6)-Hirst inverse of X(25)
X(232) = X(281)-beth conjugate of X(232)


X(233) = X(2)-CEVA CONJUGATE OF X(140)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [b cos(C - A) + c cos(B - A)]cos(B - C)
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(233) lies on these lines: 2,95   5,53   6,17   115,128   122,138

X(233) = isogonal conjugate of X(288)
X(233) = complement of X(95)
X(233) = X(2)-Ceva conjugate of X(140)
X(233) = crosspoint of X(2) and X(5)
X(233) = crosssum of X(6) and X(54)
X(233) = crossdifference of every pair of points on line X(1157)X(1510)


X(234) = X(7)-CEVA CONJUGATE OF X(177)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos B/2 + cos C/2)(cos B/2 cos C/2)2
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(234) lies on these lines: 2,178   7,174   57,362   75,556   555,1088

X(234) = X(7)-Ceva conjugate of X(177)


X(235) = X(4)-CEVA CONJUGATE OF X(185)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sec A - cos(B - C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(235) lies on these lines: 2,3   11,34   12,33   52,113   133,136

X(235) = midpoint of X(4) and X(24)
X(235) = X(4)-Ceva conjugate of X(185)
X(235) = crosssum of X(3) and X(1092)


X(236) = X(2)-CEVA CONJUGATE OF X(188)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (csc A/2)(cos B/2 + cos C/2 - cos A/2)
Trilinears       [1 + sin(A/2)]/sin A : [1 + sin(B/2)]/sin B : [1 + sin(C/2)]//sin C     (M. Iliev, 4/12/07)

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(236) lies on these lines: 2,174   8,178   9,173

X(236) = isogonal conjugate of X(289)
X(236) = X(2)-Ceva conjugate of X(188)



leftri Centers 237- 248 rightri
are line conjugates. The P-line conjugate of Q is the point
where line PQ meets the trilinear polar of the isogonal conjugate of Q.

underbar

X(237) = X(3)-LINE CONJUGATE OF X(2)

Trilinears       a2cos(A + ω) : b2cos(B + ω) : c2cos(C + ω)
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a3(b4 + c4 - a2b2 - a2c2) (Darij Grinberg, 3/29/03)

Barycentrics  a3cos(A + ω) : b3cos(B + ω) : c3cos(C + ω)

X(237) is the point of intersection of the Euler line and the Lemoine axis (defined as the radical axis of the circumcircle and the Brocard circle).

If you have The Geometer's Sketchpad, you can view X(1316), which includes X(237).

X(237) lies on these lines: 2,3   6,160   31,904   32,184   39,51   154,682   187,351   206,571

X(237) is the {X(1113),X(1114)}-harmonic conjugate of X(1316). For a list of other harmonic conjugates of X(237), click Tables at the top of this page.

X(237) = isogonal conjugate of X(290)
X(237) = X(98)-Ceva conjugate of X(6)
X(237) = crosspoint of X(I) and X(J) for these (I,J): (6,98), (232,511)
X(237) = crosssum of X(I) and X(J) for these (I,J): (2,511), (98,287)
X(237) = crossdifference of every pair of points on line X(2)X(647)
X(237) = X(32)-Hirst inverse of X(184)
X(237) = X(3)-line conjugate of X(2)
X(237) = X(55)-beth conjugate of X(237)


X(238) = X(1)-LINE CONJUGATE OF X(37)

Trilinears       a2 - bc : b2 - ca : c2 - ab
Barycentrics  a3 - abc : b3 - abc : c3 - abc

X(238) is the perspector of triangle ABC and the tangential triangle of the conic that passes through A, B, C, and the pair P(8) and U(8) of bicentric points (see the notes just before X(1908). (Randy Hutson, 9/23/2011)

X(238) lies on these lines:
1,6   2,31   3,978   4,602   7,1471   8,983   10,82   21,256   36,513   40,1722   42,1621   43,55   47,499   56,87   57,1707   58,86   63,614   71,1244   100,899   105,291   106,898   162,415   190,726   212,497   239,740   241,1456   242,419   244,896   390,1253   459,1395   484,1739   516,673   517,1052   519,765   580,946   601,631   651,1458   662,1326   942,1046   987,1472   992,1009   993,995   1006,1064   1040,1711   1054,1155   1284,1428   1465,1758   1479,1714   1699,1754

X(238) = midpoint of X(1) and X(1279)
X(238) = reflection of X(1) in X(1297)
X(238) = isogonal conjugate of X(291)
X(238) = isotomic conjugate of X(334)
X(238) = X(I)-Ceva conjugate of X(J) for these (I,J): (105,1), (292,171)
X(238) = X(659)-cross conjugate of X(3573)
X(238) = crosssum of X(I) and X(J) for these (I,J): (10,726), (42,672), (239,894)
X(238) = crossdifference of every pair of points on line X(37)X(513)
X(238) = X(I)-Hirst inverse of X(J) for these (I,J): (1,6), (43,55)
X(238) = X(1)-line conjugate of X(37)
X(238) = X(105)-aleph conjugate of X(238)
X(238) = X(I)-beth conjugate of X(J) for these (I,J): (21,238), (643,902), (644,238), (932,238)


X(239) = X(1)-LINE CONJUGATE OF X(42)

Trilinears       bc(a2 - bc) : ca(b2 - ca) : ab(c2 - ab)
Barycentrics  a2 - bc : b2 - ca : c2 - ab

X(239) is the perspector of triangle ABC and the tangential triangle of the conic that passes through A, B, C, and the pair P(6) and U(6) of bicentric points (see the notes just before X(1908). (Randy Hutson, 9/23/2011)

X(239) lies on these lines:
1,2   6,75   7,193   9,192   44,190   57,330   63,194   81,274   83,213   86,1100   92,607   141,319   238,740   241,664   257,333   294,666   318,458   320,524   335,518   514,649   1043,1104

X(239) = reflection of X(I) in X(J) for these (I,J): (190,44), (320,1086)
X(239) = isogonal conjugate of X(292)
X(239) = isotomic conjugate of X(335) X(239) = crosspoint of X(256) and X(291)
X(239) = crosssum of X(I) and X(J) for these (I,J): (3,255), (212,219)
X(239) = crossdifference of every pair of points on line X(42)X(649)
X(239) = X(I)-Hirst inverse of X(J) for these (I,J): (171,238), (665,1015)
X(239) = X(1)-line conjugate of X(42)
X(239) = X(I)-beth conjugate of X(J) for these (I,J): (333,239), (645,44)


X(240) = X(1)-LINE CONJUGATE OF X(48)

Trilinears       sec A cos(A + ω) : sec B cos(B + ω) : sec C cos(C + ω)
Barycentrics  tan A cos(A + ω) : tan B cos(B + ω) : tan C cos(C + ω)

X(240) lies on these lines: 1,19   4,256   38,92   63,1096   75,158   162,896   278,982   281,984   522,656   607,611   608,613

X(240) = isogonal conjugate of X(293)
X(240) = isotomic conjugate of X(336)
X(240) = crossdifference of every pair of points on line X(48)X(656)
X(240) = X(1)-Hirst inverse of X(19)
X(240) = X(1)-line conjugate of X(48)
X(240) = X(318)-beth conjugate of X(240)


X(241) = X(1)-LINE CONJUGATE OF X(55)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = cos4B/2 - [cos2(A/2)][cos2(B/2) +cos2(C/2)] + cos4(C/2)

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(241) lies on these lines: 1,3   2,85   6,77   7,37   9,269   44,651   63,220   141,307   218,222   239,664   277,278   294,910   347,1108   514,650   960,1042

X(241) = isogonal conjugate of X(294)
X(241) = crosssum of X(I) and X(J) for these (I,J): (6,910), (518,1376
X(241) = crossdifference of every pair of points on line X(55)X(650)
X(241) = X(1)-Hirst inverse of X(57)
X(241) = X(1)-line conjugate of X(55)
X(241) = X(I)-beth conjugate of X(J) for these (I,J): (2,241), (100,241), (1025,241), (1026,241)


X(242) = X(4)-LINE CONJUGATE OF X(71)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (sec A)(sin2A - sin B sin C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(242) lies on these lines: 4,9   25,92   28,261   29,257   34,87   162,422   238,419   278,459   915,929

X(242) = isogonal conjugate of X(295)
X(242) = isotomic conjugate of X(337)
X(242) = crossdifference of every pair of points on line X(71)X(1459)
X(242) = X(4)-Hirst inverse of X(19)
X(242) = X(4)-line conjugate of X(71)


X(243) = X(4)-LINE CONJUGATE OF X(73)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (sec A)(cos2A - cos B cos C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(243) is the perspector of triangle ABC and the tangential triangle of the conic that passes through A, B, C, and the pair P(15) and U(15) of bicentric points (see the notes just before X(1908). (Randy Hutson, 9/23/2011)

X(243) lies on these lines: 1,4   3,158   55,92   65,412   318,958   411,821   425,662   522,652   920,1075   1040,1096

X(243) = isogonal conjugate of X(296)
X(243) = crossdifference of every pair of points on line X(73)X(652)
X(243) = X(I)-Hirst inverse of X(J) for these (I,J): (1,4), (46,1148)
X(243) = X(1)-line conjugate of X(73)


X(244) = X(1)-LINE CONJUGATE OF X(100)

Trilinears       (b - c)2 : (c - a)2 : (a - b)2
                        = f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = [1 - cos(B - C)]sin2(A/2)
Barycentrics  a(b - c)2 : b(c - a)2 : c(a - b)2

X(244) lies on these lines: 1,88   2,38   11,867   31,57   34,1106   42,354   58,229   63,748   238,896   474,976   518,899   596,1089   665,866

X(244) = isogonal conjugate of X(765)
X(244) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,513), (75,514)
X(244) = crosspoint of X(1) and X(513)
X(244) = crosssum of X(I) and X(J) for these (I,J): (1,100), (31,101), (78,1331), (109,1420), (200,644), (651,1445), (678,1023), (756,1018)

X(244) = crossdifference of every pair of points on line X(100)X(101)
X(244) = X(1)-Hirst inverse of X(1054)
X(244) = X(1)-line conjugate of X(100)


X(245) = X(1)-LINE CONJUGATE OF X(110)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = csc2(C - A) + csc(C - B) [csc(C - A) -csc(B - A)] + csc2(A - B)

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(245) lies on these lines: 1,60   115,125

X(245) = X(1)-line conjugate of X(110)


X(246) = X(3)-LINE CONJUGATE OF X(110)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = csc(B-A)[cos A csc(B - A) + cos C csc(B - C)] + csc(C - A) u(A,B,C),
                        u(A,B,C) = [cos A csc(C - A) + cos B csc(C - B)]

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(246) lies on these lines: 3,74   115,125

X(246) = X(3)-line conjugate of X(110)


X(247) = X(4)-LINE CONJUGATE OF X(110)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = csc(B-A)[sec A csc(B - A) + sec C csc(B - C)] + csc(C - A) u(A,B,C),
                        u(A,B,C) = [sec A csc(C - A) + sec B csc(C - B)]

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(247) lies on these lines: 4,110   115,125

X(247) = crossdifference of every pair of points on line X(110)X(686)
X(247) = X(4)-line conjugate of X(110)


X(248) = X(4)-LINE CONJUGATE OF X(132)

Trilinears       sin 2A sec(A + ω) : sin 2B sec(B + ω) : sin 2C sec(C + ω)
Barycentrics  sin A sin 2A sec(A + ω) : sin B sin 2B sec(B + ω) : sin C sin 2C sec(C + ω)

X(248) lies on these lines:
4,32   6,157   39,54   50,67   65,172   66,571   69,287   72,293   74,187   290,385   682,695

X(248) = isogonal conjugate of X(297)
X(248) = crosspoint of X(98) and X(287)
X(248) = crosssum of X(232) and X(511)
X(248) = crossdifference of every pair of points on line X(114)X(132)
X(248) = X(4)-line conjugate of X(132)



leftri Centers 249- 297 rightri
are isogonal conjugates of previously listed centers.

underbar

X(249) = ISOGONAL CONJUGATE OF X(115)

Trilinears       (csc A)csc2(B - C) : (csc B)csc2(C - A) : (csc C)csc2(A - B)
                        = a/(b2 - c2)2 : b/(c2 - a2)2 : c/(a2 - b2)2

Barycentrics  csc2(B - C) : csc2(C - A) : csc2(A - B)

X(249) lies on these lines: 99,525   110,512   186,250   187,323   297,316   648,687   805,827   849,1110

X(249) = isogonal conjugate of X(115)
X(249) = isotomic conjugate of X(338)
X(249) = cevapoint of X(I) and X(J) for these (I,J): (6,110), (24,112)
X(249) = X(I)-cross conjugate of X(J) for these (I,J): (3,99), (6,110)


X(250) = ISOGONAL CONJUGATE OF X(125)

Trilinears       (sec A)csc2(B - C) : (sec B)csc2(C - A) : (sec C)csc2(A - B)
                        = (a2sec A)/(b2 - c2)2 : (b2sec B)/(c2 - a2)2 : (c2sec C)/(a2 - b2)2

Barycentrics  (tan A)csc2(B - C) : (tan B)csc2(C - A) : (tan C)csc2(A - B)

X(250) lies on these lines: 23,232   107,687   110,520   112,691   186,249   325,340   476,933   523,648   827,935

X(250) = isogonal conjugate of X(125)
X(250) = isotomic conjugate of X(339)
X(250) = cevapoint of X(I) and X(J) for these (I,J): (3,110), (25,112), (162,270)
X(250) = X(I)-cross conjugate of X(J) for these (I,J): (3,110), (22,99), (24,107), (25,112), (199,101)


X(251) = ISOGONAL CONJUGATE OF X(141)

Trilinears       a2csc(A + ω) : b2csc(B + ω) : c2csc(C + ω)
                        = a/(b2 + c2) : b/(c2 + a2) : c/(a2 + b2)

Barycentrics  a3csc(A + ω) : b3csc(B + ω) : c3csc(C + ω)

Let K be the symmedian point of ABC and let A' be the symmedian point of the triangle BCK; define B' and C' cyclically. The lines AA', BB', CC' concur in X(251). (Randy Hutson, 9/23/2011)

X(251) lies on these lines: 2,32   6,22   37,82   110,694   112,427   184,263   308,385   609,614   689,699

X(251) = isogonal conjugate of X(141)
X(251) = complement of X(1369)
X(251) = cevapoint of X(6) and X(32)
X(251) = X(I)-cross conjugate of X(J) for these (I,J): (6,83), (23,111), (523,112)


X(252) = ISOGONAL CONJUGATE OF X(143)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = sec(B - C)/[1 - 2 cos(2A)]

Trilinears       h(A,B,C) : h(B,C,A) : h(C,A,B), where
                        h(A,B,C) = cos A sec(3A) sec(B - C) (Manol Iliev, 4/01/07)

Barycentrics   (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C) f(C,A,B)

X(252) lies on these lines: 3,930   54,140   93,186

X(252) = isogonal conjugate of X(143)


X(253) = X(4)-CROSS CONJUGATE OF X(2)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (csc A)/(tan B + tan C - tan A)
                         = g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (csc2A)/(cos A - cos B cos C)

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = 1/(tan B + tan C - tan A)

X(253) is the perspector of ABC and the pedal triangle of X(64).

X(253) lies on these lines: 2,1073   7,280   8,307   20,64   193,287   306,329   318,342   322,341

X(253) = isogonal conjugate of X(154)
X(253) = isotomic conjugate of X(20)
X(253) = cyclocevian conjugate of X(69)
X(253) = cevapoint of X(I) and X(J) for these (I,J): (4,459), (122,525)
X(253) = X(I)-cross conjugate of X(J) for these (I,J): (4,2), (122,525)


X(254) = X(3)-CROSS CONJUGATE OF X(4)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (sec A)/(cos2B + cos2C - cos2A)
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (tan A)/(cos2B + cos2C - cos2A)

X(254) lies on these lines: 2,847   4,155   24,393   46,225   68,136

X(254) = isogonal conjugate of X(155)
X(254) = cevapoint of X(136) and X(523)
X(254) = X(3)-cross conjugate of X(4)


X(255) = ISOGONAL CONJUGATE OF X(158)

Trilinears       cos2A : cos2B : cos2C
                        = 1 + cos 2A : 1 + cos 2B : 1 + cos 2C

Barycentrics  sin A cos2A : sin B cos2B : sin C cos2C

X(255) lies on these lines: 1,21   3,73   35,991   36,1106   40,109   48,563   55,601   56,602   57,580   91,1109   92,1087   158,775   162,1099   165,1103   200,271   201,1060   219,268   293,304   326,1102   411,651   498,750   499,748

X(255) = isogonal conjugate of X(158)
X(255) = X(I)-Ceva conjugate of X(J) for these (I,J): (63,48), (283,3)
X(255) = crosspoint of X(63) and X(326)
X(255) = crosssum of X(I) and X(J) for these (I,J): (1,290), (4,1068), (19,1096)
X(255) = X(I)-aleph conjugate of X(J) for these (I,J): (775,255), (1105,158)


X(256) = 1st SHARYGIN POINT

Trilinears       1/(a2 + bc) : 1/(b2 + ca) : 1/(c2 + ab)
Barycentrics  a/(a2 + bc) : b/(b2 + ca) : c/(c2 + ab)

See the description at X(1281). The lines AD, BE, CF defined there concur in X(256).

X(256) lies on these lines: 1,511   3,987   4,240   7,982   8,192   9,43   21,238   37,694   40,989   55,983   84,988   104,1064   291,894   314,350   573,981

X(256) = isogonal conjugate of X(171)
X(256) = isotomic conjugate of X(1909)
X(256) = X(239)-cross conjugate of X(291)
X(256) = crosssum of X(43) and X(846)
X(256) = X(238)-Hirst inverse of X(904)


X(257) = ISOGONAL CONJUGATE OF X(172)

Trilinears       1/(a3 + abc) : 1/(b3 + abc) : 1/(c3 + abc)
Barycentrics  1/(a2 + bc) : 1/(b2 + ca) : 1/(c2 + ab)

X(257) lies on these lines: 1,385   8,192   29,242   65,894   75,698   92,297   194,986   239,333   330,982   335,694

X(257) = isogonal conjugate of X(172)
X(257) = isotomic conjugate of X(894)
X(257) = X(350)-cross conjugate of X(335)
X(257) = X(239)-Hirst inverse of X(893)


X(258) = CONGRUENT INCIRCLES ISOSCELIZER POINT

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/(cos B/2 + cos C/2 - cos A/2)
                        = g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = 1 + sin(B/2) + sin(C/2) - sin(A/2)
Trilinears       tan(A/2) - sec(A/2) : tan(B/2) - sec(B/2) : tan(C/2) - sec(C/2)     (M. Iliev, 4/12/07)

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

In Yff's isoscelizer configuration, if X = X(258), then the isosceles triangles TA, TB, TC have congruent incircles.

X(258) is the perspector of ABC and the extouch triangle of the intouch triangle.

If you have The Geometer's Sketchpad, you can view X(258).

X(258) lies on these lines: 1,164   57,173   259,289

X(258) = isogonal conjugate of X(173)
X(258) = X(259)-cross conjugate of X(1)
X(258) = X(366)-aleph conjugate of X(363)


X(259) = ISOGONAL CONJUGATE OF X(174)

Trilinears       cos A/2 : cos B/2 : cos C/2
                        = [a(b + c - a)]1/2 : [b(c + a - b)]1/2 : [c(a + b - c)]1/2

Barycentrics  sin A cos A/2 : sin B cos B/2 : sin C cos C/2

X(259) lies on these lines: 1,168   258,289   260,266

X(259) = isogonal conjugate of X(174)
X(259) = X(I)-Ceva conjugate of X(J) for these (I,J): (174,266), (260,55)
X(259) = cevapoint of X(1) and X(503)
X(259) = crosspoint of X(I) and X(J) for these (I,J): (1,258), (174,188)
X(259) = crosssum of X(I) and X(J) for these (I,J): (1,173), (259,266)


X(260) = ISOGONAL CONJUGATE OF X(177)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos A/2)/(cos B/2 + cos C/2)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(260) lies on these lines: 1,3   259,266

X(260) = isogonal conjugate of X(177)
X(260) = cevapoint of X(55) and X(259)


X(261) = ISOTOMIC CONJUGATE OF X(12)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = [(csc A)(sec(B/2 - C/2))]2
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(261) lies on these lines:
2,593   9,645   21,314   28,242   58,86   75,99   272,310   284,332   317,406   319,502   552,873   572,662

X(261) = isogonal conjugate of X(181)
X(261) = isotomic conjugate of X(12)
X(261) = X(873)-Ceva conjugate of X(1509)
X(261) = cevapoint of X(21) and X(333)


X(262) = ISOGONAL CONJUGATE OF X(182)

Trilinears       sec(A - ω) : sec(B - ω) : sec(C - ω)
Barycentrics  sin A sec(A - ω) : sin B sec(B - ω) : sin C sec(C - ω)

X(262) lies on these lines: 2,51   3,83   4,39   5,76   6,98   13,383   14,1080   25,275   30,598   226,982   381,671   385,576

X(262) = isogonal conjugate of X(182)
X(262) = isotomic conjugate of X(183)


X(263) = ISOGONAL CONJUGATE OF X(183)

Trilinears       a2sec(A - ω) : b2sec(B - ω) : c2sec(C - ω)
Barycentrics  a3sec(A - ω) : b3sec(B - ω) : c3sec(C - ω)

X(263) lies on these lines: 2,51   6,160   69,308   184,251

X(263) = isogonal conjugate of X(183)


X(264) = ISOTOMIC CONJUGATE OF CIRCUMCENTER

Trilinears       csc A csc 2A : csc B csc 2B : csc C csc 2C
                        = sec A csc2A : sec B csc2B : sec C csc2C
                        = tan A csc(A - ω) : tan B csc(B - ω) : tan C csc(C - ω)

Barycentrics  csc 2A : csc 2B : csc 2C

X(264) lies on these lines:
2,216   3,95   4,69   5,1093   6,287   25,183   33,350   53,141   75,225   85,309   92,306   99,378   274,475   281,344   298,472   299,473   300,302   301,303   305,325   339,381   379,823   401,577

X(264) = isogonal conjugate of X(184)
X(264) = isotomic conjugate of X(3)
X(264) = complement of X(3164)
X(264) = anticomplement of X(216)
X(264) = X(276)-Ceva conjugate of X(2)
X(264) = cevapoint of X(I) and X(J) for these (I,J): (2,4), (5,324), (6,157), (92,318), (273,342), (338,523), (491,492)

X(264) = X(I)-cross conjugate of X(J) for these (I,J): (2,76), (5,2), (30,94), (92,331), (427,4), (442,321)


X(265) = REFLECTION OF X(3) IN X(125)

Trilinears       sin 2A csc 3A : sin 2B csc 3B : sin 2C csc 3C
                        = 1/(4 cos A - sec A) : 1/(4 cos B - sec B) : 1/(4 cos C sec C)
Barycentrics  sin A sin 2A csc 3A : sin B sin 2B csc 3B : sin C sin 2C csc 3C

Let P = X(74), H = X(4), H' =H-of-BCP, H'' = H-of-CAP, and H''' = H-of ABP. Then X(265) is the circumcenter of the cyclic quadrilateral HH'H''H'''. (Randy Hutson, 9/23/2011)

Let A' be the reflection in line BC of the A-vertex of the tangential triangle, and define B' and C' cyclically. The circumcircles of A'BC, B'CA, and C'AB concur in X(265). Let A'' be the reflection in line BC of the A-vertex of the anticevian triangle of X(5), and define B'' and C'' cyclically. The circumcircles of AB''C'', BC''A'', CA''B'' concur in X(265). (Randy Hutson, August 26, 2014)

Let A*B*C* be the Kosnita triangle. Let A' be the orthopole of line B*C*, and define B' and C' cyclically. The lines AA', BB', CC' concur in X(265). (Randy Hutson, August 26, 2014)

Let A'B'C' be the X(3)-Fuhrmann triangle. Let A'' be the reflection of A in line B'C', and define B'' and C'' cyclically. Then A''B''C'' isinversely similar to ABC, with similtude center X(265), and A''B''C'' is perspective to ABC with persepctor X(74). (Randy Hutson, August 26, 2014)

Let A'B'C' be the reflection triangle. Let L be the line through A' parallel to the Euler line, and define M and N cyclically. Let L' be the reflection of L in sideline BC, and define M' and N' cyclically. The lines L',M', N' concur in X(265). (Randy Hutson, August 26, 2014)

X(265) lies on these lines: 3,125   4,94   5,49   6,13   30,74   64,382   65,79   67,511   69,328   290,316   300,621   301,622

X(265) = midpoint of X(4) and X(3448)
X(265) = reflection of X(I) in X(J) for these (I,J): (3,125), (110,5), (146,1539), (399,113)
X(265) = isogonal conjugate of X(186)
X(265) = isotomic conjugate of X(340)
X(265) = anticomplement of X(1511)
X(265) = cevapoint of X(5) and X(30)
X(265) = crosspoint of X(94) and X(328)
X(265) = inverse-in-circumcircle of X(5961)
X(265) = antigonal image of X(3)
X(265) = symgonal of X(5)
X(265) = Johnson-circumconic antipode of X(110)
X(276) = trilinear pole of line X(216)X(647)
X(276) = inverse-in-Kiepert-hyperbola of X(1989)
X(276) = {X(13),X(14)}-harmonic conjugate of X(1989)
X(276) = X(92)-isoconjugate of X(50)
X(276) = Hofstadter -2 point


X(266) = ISOGONAL CONJUGATE OF X(188)

Trilinears       sin A/2 : sin B/2 : sin C/2
                        = [a/(b + c - a)]1/2 : [b/(c + a - b)]1/2 : [c/(a + b - c)]1/2

Barycentrics  sin A sin A/2 : sin B sin B/2 : sin C sin C/2

X(266) lies on these lines:1,164   56,289   174,188   259,260   361,978

X(266) = isogonal conjugate of X(188)
X(266) = eigencenter of cevian triangle of X(174)
X(266) = eigencenter of anticevian triangle of X(259)
X(266) = X(174)-Ceva conjugate of X(259)
X(266) = cevapoint of X(1) and X(361)
X(266) = X(6)-cross conjugate of X(289)
X(266) = crosspoint of X(1) and X(505)
X(266) = crosssum of X(1) and X(164)


X(267) = ISOGONAL CONJUGATE OF X(191)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = 1/[b3 + c3 - a3 + (b + c - a)(bc + ca + ab)]

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(267) lies on these lines: 1,229   10,191   35,37

X(267) = reflection of X(1) in X(229)
X(267) = isogonal conjugate of X(191)
X(267) = cevapoint of X(58) and X(501)
X(267) = X(58)-cross conjugate of X(1)


X(268) = ISOGONAL CONJUGATE OF X(196)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos A cot A/2)/(-1 - cos A + cos B + cos C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(268) lies on these lines: 3,9   21,280   219,255   220,577   222,1073   281,1012

X(268) = isogonal conjugate of X(196)
X(268) = X(I)-cross conjugate of X(J) for these (I,J): (48,219), (55,3)
X(268) = crosssum of X(19) and X(207)


X(269) = ISOGONAL CONJUGATE OF X(200)

Trilinears       tan2A/2 : tan2B/2 : tan2C/2

                        = [a2 - (b - c)2]2 : [b2 - (c - a)2]2 : [c2 - (a - b)2]2 Barycentrics  sin A tan2A/2 : sin B tan2B/2 : sin C tan2C/2

X(269) lies on these lines: 1,7   3,939   6,57   9,241   46,1103   56,738   69,200   86,1088   106,934   142,948   273,1111   292,1020   307,936   320,326   479,614

X(269) = isogonal conjugate of X(200)
X(269) = isotomic conjugate of X(341)
X(269) = X(279)-Ceva conjugate of X(57)
X(269) = X(56)-cross conjugate of X(57)
X(269) = crosspoint of X(279) and X(479)
X(269) = crosssum of X(220) and X(480)


X(270) = ISOGONAL CONJUGATE OF X(201)

Trilinears       (sec A)/[1 + cos(B - C)] : (sec B)/[1 + cos(C - A)] : (sec C)/[1 + cos(A - B)]
Barycentrics  (tan A)/[1 + cos(B - C)] : (tan B)/[1 + cos(C - A)] : (tan C)/[1 + cos(A - B)]

X(270) lies on these lines: 4,162   27,58   28,60   29,283   759,933

X(270) = isogonal conjugate of X(201)
X(270) = X(250)-Ceva conjugate of X(162)
X(270) = cevapoint of X(28) and X(58)
X(270) = X(58)-cross conjugate of X(60)


X(271) = ISOGONAL CONJUGATE OF X(208)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cot A cot A/2)/(-1 - cos A + cos B + cos C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(271) lies on these lines: 2,1034   8,20   78,394   200,255   282,283

X(271) = isogonal conjugate of X(208)
X(271) = isotomic conjugate of X(342)
X(271) = X(I)-cross conjugate of X(J) for these (I,J): (3,78), (9,63)


X(272) = ISOGONAL CONJUGATE OF X(209)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = 1/[(sin A + sin(A - B) + sin(A - C))(sin B + sin C)]

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(272) lies on these lines: 2,284   7,58   21,75   28,273   60,86   261,310   1014,1088

X(272) = isogonal conjugate of X(209)
X(272) = X(3)-cross conjugate of X(81)


X(273) = ISOGONAL CONJUGATE OF X(212)

Trilinears       sec A sec2(A/2) : sec B sec2(B/2) : sec C sec2(C/2)
                        = (1- sec A)csc2A : (1 - sec B)csc2B : (1 - sec C)csc2C

Barycentrics  tan A sec2(A/2) : tan B sec2(B/2) : tan C sec2(C/2)

X(273) lies on these lines: 2,92   4,7   19,653   27,57   28,272   29,34   53,1086   75,225   78,322   108,675   226,469   269,1111   317,320   458,894

X(273) = isogonal conjugate of X(212)
X(273) = isotomic conjugate of X(78)
X(273) = X(I)-Ceva conjugate of X(J) for these (I,J): (264,342), (286,7), (331,92)
X(273) = cevapoint of X(I) and X(J) for these (I,J): (4,278), (34,57)
X(273) = X(I)-cross conjugate of X(J) for these (I,J): (4,92), (57,85), (225,278)


X(274) = ISOGONAL CONJUGATE OF X(213)

Trilinears       b2c2/(b + c) : c2a2/(c + a) : a2b2/(a + b)
                        = [a csc(A - ω)]/(b + c) : [b csc(B - ω)]/(c + a) :[c csc(C - ω)]/(a + b)

Barycentrics  bc/(b + c) : ca/(c + a) : ab/(a + b)

X(274) lies on these lines:
1,75   2,39   7,959   10,291   21,99   28,242   57,85   58,870   69,443   81,239   88,799   110,767   183,474   213,894   264,475   278,331   315,377   325,442   961,1014

X(274) = isogonal conjugate of X(213)
X(274) = isotomic conjugate of X(37)
X(274) = complement of X(1655)
X(274) = X(310)-Ceva conjugate of X(314)
X(274) = cevapoint of X(I) and X(J) for these (I,J): (2,75), (85,348), (86,333)
X(274) = X(I)-cross conjugate of X(J) for these (I,J): (2,86), (75,310), (81,286), (333,314)
X(274) = crossdifference of every pair of points on line X(669)X(798)


X(275) = CEVAPOINT OF ORTHOCENTER AND SYMMEDIAN POINT

Trilinears       csc 2A sec(B - C) : csc 2B sec(C - A) : csc 2C sec(A - B)
Barycentrics  sec A sec(B - C) : sec B sec(C - A) : sec C sec(A - B)

X(275) lies on these lines:
2,95   4,54   13,472   14,473   17,471   18,470   25,262   51,107   53,288   76,276   83,297   94,324   98,427

X(275) = isogonal conjugate of X(216)
X(275) = isotomic conjugate of X(343)
X(275) = X(276)-Ceva conjugate of X(95)
X(275) = cevapoint of X(4) and X(6)
X(275) = X(I)-cross conjugate of X(J) for these (I,J): (6,54), (54,95)
X(275) = crosssum of X(217) and X(418)


X(276) = ISOGONAL CONJUGATE OF X(217)

Trilinears       csc3A sec A sec(B - C) : csc3B sec B sec(C - A) : csc3C sec C sec(A - B)
Barycentrics  csc2A sec A sec(B - C) : csc2B sec B sec(C - A) : csc2C sec C sec(A - B)

X(276) lies on these lines: 3,95   4,327   54,290   76,275   97,401

X(276) = isogonal conjugate of X(217)
X(276) = isotomic conjugate of X(216)
X(276) = cevapoint of X(I) and X(J) for these (I,J): (2,264), (95,275)
X(276) = X(I)-cross conjugate of X(J) for these (I,J): (2,95), (401,290)


X(277) = ISOGONAL CONJUGATE OF X(218)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = [sec2(A/2)]/[- cos4A/2 + cos4B/2 + cos4C/2]
Barycentrics  af(A,B,C) : bf(B,C,A) : cf(C,A,B)

X(277) lies on these lines: 1,142   3,105   7,218   57,169   220,1086   241,278   942,1002

X(277) = isogonal conjugate of X(218)
X(277) = isotomic conjugate of X(344)
X(277) = X(55)-cross conjugate of X(7)


X(278) = ISOGONAL CONJUGATE OF X(219)

Trilinears       sec A tan A/2 : sec B tan B/2 : sec C tan C/2
                        = csc A - 2 csc 2A : csc B - 2 csc 2B : csc C - 2 csc 2C
                        = (1 - sec A)/a : (1 - sec B)/b : (1 - sec C)/c
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc/[(b + c - a)(b2 + c2 - a2)]

Barycentrics  tan A tan A/2 : tan B tan B/2 : tan C tan C/2

        nbsp;= 1 - sec A : 1 - sec B : 1 - sec C

X(278) lies on these lines:
1,4   2,92   7,27   19,57   25,105   28,56   65,387   88,653   109,917   219,329   240,982   241,277   242,459   274,331   354,955   393,1108   412,962   443,1038   614,1096

X(278) = isogonal conjugate of X(219)
X(278) = isotomic conjugate of X(345)
X(278) = X(I)-Ceva conjugate of X(J) for these (I,J): (27,57), (92,196), (273,4), (331,7)
X(278) = cevapoint of X(19) and X(34)
X(278) = X(I)-cross conjugate of X(J) for these (I,J): (19,4), (56,7), (225,273)


X(279) = ISOGONAL CONJUGATE OF X(220)

Trilinears       csc A tan2A/2 : csc B tan2B/2 : csc C tan2C/2
                        = bc[a2 - (b - c)2]2 : ca[b2 - (c - a)2]2 : ab[c2 - (a - b)2]2

Barycentrics  tan2A/2 : tan2B/2 : tan2C/2

X(279) lies on these lines: 1,7   2,85   28,1014   56,105   57,479   65,1002   144,220   145,664   304,346   942,955   985,1106

X(279) = isogonal conjugate of X(220)
X(279) = isotomic conjugate of X(346)
X(279) = cevapoint of X(57) and X(269)
X(279) = X(I)-cross conjugate of X(J) for these (I,J): (57,7), (269,479)
X(279) = crosssum of X(1) and X(170)


X(280) = X(1)-CROSS CONJUGATE OF X(8)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (csc2A/2)/(-1 - cos A + cos B + cos C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(280) lies on these lines: 2,318   7,253   8,20   21,268   75,309   78,282   285,1043   341,345

X(280) = isogonal conjugate of X(221)
X(280) = isotomic conjugate of X(347)
X(280) = X(309)-Ceva conjugate of X(189)
X(280) = cevapoint of X(1) and X(84)
X(280) = X(I)-cross conjugate of X(J) for these (I,J): (1,8), (281,2), (282,189)


X(281) = X(37)-CROSS CONJUGATE OF X(9)

Trilinears       sec A cot A/2 : sec B cot B/2 : sec C cot C/2
                        = csc A + 2 csc 2A : csc B + 2 csc 2B : csc C + 2 csc 2C
                        = (1 + sec A)/a : (1 + sec B)/b : (1 + sec C)/c

Barycentrics  tan A cot A/2 : tan B cot B/2 : tan C cot C/2
        = 1 + sec A : 1 + sec B : 1 + sec C

X(281) lies on these lines:
1,282   2,92   4,9   7,653   8,29   28,958   33,200   37,158   45,53   48,944   100,1013   189,222   196,226   220,594   240,984   264,344   268,1012   318,346   380,950   451,1068   515,610   612,1096

X(281) = isogonal conjugate of X(222)
X(281) = isotomic conjugate of X(348)
X(281) = complement of X(347)
X(281) = X(I)-Ceva conjugate of X(J) for these (I,J): (29,33), (92,4)
X(281) = X(I)-cross conjugate of X(J) for these (I,J): (33,4), (37,9), (55,8)
X(281) = crosspoint of X(I) and X(J) for these (I,J): (2,280), (92,318)
X(281) = crosssum of X(I) and X(J) for these (I,J): (6,221), (48,603), (73,1409), (652,1364)


X(282) = X(6)-CROSS CONJUGATE OF X(9)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cot A/2)/(-1 - cos A + cos B + cos C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(282) lies on the Thomson cubic and these lines:
1,281   2,77   3,9   4,3351   6,3341   19,102   48,947   57,3343   78,280   200,219   271,283   380,1036

X(282) = isogonal conjugate of X(223)
X(282) = X(189)-Ceva conjugate of X(84)
X(282) = X(I)-cross conjugate of X(J) for these (I,J): (6,9), (33,1)
X(282) = crosspoint of X(189) and X(280)
X(282) = crosssum of X(I) and X(J) for these (I,J): (6,1035), (198,221)


X(283) = X(3)-CROSS CONJUGATE OF X(21)

Trilinears       (cos A)/(cos B + cos C) : (cos B)/(cos C + cos A) : (cos C)/(cos A + cos B)
Barycentrics  (sin 2A)/(cos B + cos C) : (sin 2B)/(cos C + cos A) : (sin 2C)/(cos A + cos B)

X(283) lies on these lines: 1,21   2,580   3,49   29,270   60,284   77,603   78,212   86,307   102,110   271,282   474,582   643,1043   859,945   1010,1065

X(283) = isogonal conjugate of X(225)
X(283) = X(333)-Ceva conjugate of X(284)
X(283) = cevapoint of X(I) and X(J) for these (I,J): (3,255), (212,219)
X(283) = X(3)-cross conjugate of X(21)
X(283) = crosspoint of X(332) and X(333)


X(284) = X(55)-CROSS CONJUGATE OF X(21)

Trilinears       (sin A)/(cos B + cos C) : (sin B)/(cos C + cos A) : (sin C)/(cos A + cos B)
Barycentrics  a2/(cos B + cos C) : b2/(cos C + cos A) : c2/(cos A + cos B)
X(284) = s*X(3) + (r + 2R)*cot(ω)*X(6)

X(284) lies on these lines:
1,19   2,272   3,6   9,21   27,226   29,950   35,71   37,101   55,219   57,77   60,283   73,951   86,142   102,112   109,296   163,909   198,859   261,332   405,965   501,942   515,1065

X(284) = isogonal conjugate of X(226)
X(284) = isotomic conjugate of X(349)
X(284) = inverse-in-Brocard-circle of X(579)
X(284) = X(I)-Ceva conjugate of X(J) for these (I,J): (81,58), (333,283)
X(284) = cevapoint of X(I) and X(J) for these (I,J): (6,48), (41,55)
X(284) = X(55)-cross conjugate of X(21)
X(284) = crosspoint of X(I) and X(J) for these (I,J): (21,81), (29,333)
X(284) = crosssum of X(I) and X(J) for these (I,J): (37,65), (73,1400)
X(284) = crossdifference of every pair of points on line X(523)X(656)


X(285) = X(58)-CROSS CONJUGATE OF X(21)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = 1/[(cos B + cos C)(-1 - cos A + cos B + cos C)]

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(285) lies on these lines: 21,84   29,81   271,282   280,1043

X(285) = isogonal conjugate of X(227)
X(285) = X(58)-cross conjugate of X(21)


X(286) = X(4)-CROSS CONJUGATE OF X(27)

Trilinears       (csc 2A)/(sin B + sin C) : (csc 2B)/(sin C + sin A) : (csc 2C)/(sin A + sin B)
Barycentrics  (sec A)/(sin B + sin C) : (sec B)/(sin C + sin A) : (sec C)/(sin A + sin B)

X(286) lies on these lines: 4,69   7,331   19,27   28,242   29,34   99,915   112,767   158,969   322,1043

X(286) = isogonal conjugate of X(228)
X(286) = isotomic conjugate of X(72)
X(286) = cevapoint of X(I) and X(J) for these (I,J): (4,92), (7,273), (27,29), (28,81)
X(286) = X(I)-cross conjugate of X(J) for these (I,J): (4,27), (7,86), (81,274)


X(287) = X(2)-HIRST INVERSE OF X(98)

Trilinears       cot A sec(A + ω) : cot B sec(B + ω) : cot C sec(C + ω)
Barycentrics  cos A sec(A + ω) : cos B sec(B + ω) : cos C sec(C + ω)

X(287) lies on these lines:
2,98   6,264   69,248   83,217   95,141   185,384   193,253   293,306   297,685   305,394   401,511   651,894   879,895

X(287) = reflection of X(648) in X(6)
X(287) = isogonal conjugate of X(232)
X(287) = isotomic conjugate of X(297)
X(287) = X(290)-Ceva conjugate of X(98)
X(287) = cevapoint of X(2) and X(401)
X(287) = X(248)-cross conjugate of X(98)
X(287) = X(2)-Hirst inverse of X(98)


X(288) = CEVAPOINT OF X(6) AND X(54)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = [sec(B - C)]/[b cos(C - A) + c cos(B - A)]
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(288) lies on these lines: 51,54   53,275   97,216

X(288) = isogonal conjugate of X(233)
X(288) = cevapoint of X(6) and X(54)


X(289) = ISOGONAL CONJUGATE OF X(236)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (sin A/2)/(cos B/2 + cos C/2 - cos A/2)
Trilinears       [1 - sin(A/2)] tan(A/2) : [1 - sin(B/2)] tan(B/2) : [1 - sin(C/2)] tan(C/2)     (M. Iliev, 4/12/07)

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(289) lies on these lines: 1,363   56,266   258,259

X(289) = isogonal conjugate of X(236)
X(289) = X(6)-cross conjugate of X(266)
X(289) = crosssum of X(1) and X(363)


X(290) = ISOGONAL CONJUGATE OF X(237)

Trilinears       csc2A sec(A + ω) : csc2B sec(B + ω) : csc2C sec(C + ω)
Barycentrics  csc A sec(A + ω) : csc B sec(B + ω) : csc C sec(C + ω)

If you have The Geometer's Sketchpad, you can view the following dynamic sketch:

X(290).

X(290) lies on the Steiner circumellipse and these lines:
2,327   3,76   6,264   54,276   66,317   67,340   68,315   69,670   71,190   72,668   73,336   248,385   265,316   308,311   892,895

X(290) = isogonal conjugate of X(237)
X(290) = isotomic conjugate of X(511)
X(290) = cevapoint of X(I) and X(J) for these (I,J): (2,511), (98,287)
X(290) = X(I)-cross conjugate of X(J) for these (I,J): (385,308), (401,276), (511,2)


X(291) = 2nd SHARYGIN POINT

Trilinears       1/(a2 - bc) : 1/(b2 - ca) : 1/(c2 - ab)
Barycentrics  a/(a2 - bc) : b/(b2 - ca) : c/(c2 - ab)

See the description at X(1281). The lines AD', BE', CF' defined there concur in X(256).

X(291) lies on these lines: 1,39   2,38   6,985   8,330   10,274   42,81   43,57   88,660   105,238   256,894   337,986   350,726   659,897   876,891

X(291) = reflection of X(I) in X(J) for these (I,J): (1,1015), (668,10)
X(291) = isogonal conjugate of X(238)
X(291) = isotomic conjugate of X(350)
X(291) = X(I)-cross conjugate of X(J) for these (I,J): (239,256), (518,1)
X(291) = X(I)-Hirst inverse of X(J) for these (I,J): (1,292), (2,335)


X(292) = X(1)-HIRST INVERSE OF X(291)

Trilinears       a/(a2 - bc) : b/(b2 - ca) : c/(c2 - ab)
Barycentrics  a2/(a2 - bc) : b2/(b2 - ca) : c2/(c2 - ab)

X(292) lies on these lines: 1,39   2,334   6,869   9,87   37,86   44,660   58,101   106,813   171,893   269,1020   659,665

X(292) = isogonal conjugate of X(239)
X(292) = isotomic conjugate of X(1921)
X(292) = X(I)-Ceva conjugate of X(J) for these (I,J): (335,292), (813,3572)
X(292) = cevapoint of X(171) and X(238)
X(292) = crossdifference of every pair of points on line X(659)X(812)
X(292) = X(1)-Hirst inverse of X(291)


X(293) = ISOGONAL CONJUGATE OF X(240)

Trilinears       cos A sec(A + ω) : cos B sec(B + ω) : cos C sec(C + ω)
Barycentrics  sin 2A sec(A + ω) : sin 2B sec(B + ω) : sin 2C sec(C + ω)

X(293) lies on these lines: 1,163   31,92   72,248   98,109   255,304   287,306

X(293) = isogonal conjugate of X(240)


X(294) = ISOGONAL CONJUGATE OF X(241)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (b + c - a)/(b2 + c2 - ab - ac)
Barycentrics  af(a,b,c) : bf(b,c,a) :cf(c,a,b)

X(294) lies on these lines: 1,41   2,949   4,218   6,7   8,220   19,1041   84,580   104,919   239,666   241,910   314,645

X(294) = isogonal conjugate of X(241)
X(294) = crosssum of X(I) and X(J) for these (I,J): (672,1458), (910,1279)
X(294) = crossdifference of every pair of points on line X(926)X(1362)
X(294) = X(1)-Hirst inverse of X(105)


X(295) = ISOGONAL CONJUGATE OF X(242)

Trilinears       (cos A)/(a2 - bc) : (cos B)/(b2 - ca) : (cos C)/(c2 - ab)
Barycentrics  (sin 2A)/(a2 - bc) : (sin 2B)/(b2 - ca) : (sin 2C)/(c2 - ab)

X(295) lies on these lines: 27,335   43,57   58,101   72,337   103,813   150,334   875,926   876,928

X(295) = isogonal conjugate of X(242)
X(295) = X(335)-Ceva conjugate of X(292)
X(295) = crosspoint of X(335) and X(337)


X(296) = ISOGONAL CONJUGATE OF X(243)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (cos A)/[cos2A - cos B cos C]
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where
                        g(A,B,C) = (sin 2A)/[cos2A - cos B cos C]

X(296) lies on these lines: 1,185   3,820   29,65   109,284

X(296) = isogonal conjugate of X(243)


X(297) = X(2)-HIRST INVERSE OF X(4)

Trilinears       csc 2A cos(A + ω) : csc 2B cos(B + ω) : csc 2C cos(C + ω)
Barycentrics  sec A cos(A + ω) : sec B cos(B + ω) : sec C cos(C + ω)

X(297) lies on these lines:
2,3   6,317   53,141   69,393   76,343   83,275   92,257   232,325   249,316   287,685   315,394   340,524   525,850

X(297) = midpoint of X(340) and X(648)
X(297) = reflection of X(401) in X(441)
X(297) = isogonal conjugate of X(248)
X(297) = isotomic conjugate of X(287)
X(297) = inverse-in-orthocentroidal-circle of X(458)
X(297) = complement of X(401)
X(297) = anticomplement of X(441)
X(297) = cevapoint of X(232) and X(511)
X(297) = X(511)-cross conjugate of X(325)
X(297) = crossdifference of every pair of points on line X(184)X(647)
X(297) = X(I)-Hirst inverse of X(J) for (I,J) = (2,4), (193,1249)



leftri Centers 298- 350 rightri
are isotomic conjugates of previously listed centers.

underbar

X(298)  ISOTOMIC CONJUGATE OF 1st ISOGONIC CENTER

Trilinears       csc2A sin(A + π/3) : csc2B sin(B + π/3) : csc2C sin(C + π/3)
Barycentrics  csc A sin(A + π/3) : csc B sin(B + π/3) : csc C sin(C + π/3)

X(298) lies on these lines:
2,6   3,617   5,634   13,532   14,76   15,533   18,636   99,531   140,628   264,472   316,530   317,473   319,1082   340,470   381,622   511,1080

X(298) = midpoint of X(616) and X(621)
X(298) = reflection of X(I) in X(J) for these (I,J): (13,623), (15,618), (299,325), (385,395)
X(298) = isogonal conjugate of X(3457)
X(298) = isotomic conjugate of X(13)
X(298) = complement of X(3180)
X(298) = anticomplement of X(396)
X(298) = X(300)-Ceva conjugate of X(303)
X(298) = X(15)-cross conjugate of X(470)
X(298) = X(2)-Hirst inverse of X(299)


X(299) = ISOTOMIC CONJUGATE OF 2nd ISOGONIC CENTER

Trilinears       csc2A sin(A - π/3) : csc2B sin(B - π/3) : csc2C sin(C - π/3)
Barycentrics  csc A sin(A - π/3) : csc B sin(B - π/3) : csc C sin(C - π/3)

X(299) lies on these lines:
2,6   3,616   5,633   13,76   14,533   16,532   17,635   30,617   75,554   99,530   140,627   264,473   316,531   317,472   319,559   340,471   381,621   383,511

X(299) = midpoint of X(617) and X(622)
X(299) = reflection of X(I) in X(J) for these (I,J): (14,624), (16,619), (298,325), (385,396)
X(299) = isogonal conjugate of X(3458)
X(299) = isotomic conjugate of X(14)
X(299) = complement of X(3181)
X(299) = anticomplement of X(395)
X(299) = X(301)-Ceva conjugate of X(302)
X(299) = X(16)-cross conjugate of X(471)
X(299) = X(2)-Hirst inverse of X(298)


X(300)  ISOTOMIC CONJUGATE OF 1st ISODYNAMIC CENTER

Trilinears       csc2A csc(A + π/3) : csc2B csc(B + π/3) : csc2C csc(C + π/3)
Barycentrics  csc A csc(A + π/3) : csc B csc(B + π/3) : csc C csc(C + π/3)

X(300) lies on these lines: 2,94   13,76   264,302   265,621   303,311

X(300) = isotomic conjugate of X(15)
X(300) = cevapoint of X(298) and X(303)
X(300) = X(94)-Hirst inverse of X(301)


X(301)  ISOTOMIC CONJUGATE OF 2nd ISODYNAMIC CENTER

Trilinears       csc2A csc(A - π/3) : csc2B csc(B - π/3) : csc2C csc(C - π/3)
Barycentrics  csc A csc(A - π/3) : csc B csc(B - π/3) : csc C csc(C - π/3)

X(301) lies on these lines: 2,94   14,76   264,303   265,622   302,311

X(301) = isotomic conjugate of X(16)
X(301) = cevapoint of X(299) and X(302)
X(301) = X(94)-Hirst inverse of X(300)


X(302)  ISOTOMIC CONJUGATE OF 1st NAPOLEON POINT

Trilinears       csc2A sin(A + π/6) : csc2B sin(B + π/6) : csc2C sin(C + π/6)
Barycentrics  csc A sin(A + π/6) : csc B sin(B + π/6) : csc C sin(C + π/6)

If you have The Geometer's Sketchpad, you can view X(302).

X(302) lies on these lines:
2,6   3,621   5,622   14,99   16,316   18,76   61,629   140,633   264,300   301,311   317,470   381,616   549,617

X(302) = isotomic conjugate of X(17)
X(302) = X(301)-Ceva conjugate of X(299)
X(302) = X(61)-cross conjugate of X(473)


X(303)  ISOTOMIC CONJUGATE OF 2nd NAPOLEON POINT

Trilinears       csc2A sin(A - π/6) : csc2B sin(B - π/6) : csc2C sin(C - π/6)
Barycentrics  csc A sin(A - π/6) : csc B sin(B - π/6) : csc C sin(C - π/6)

If you have The Geometer's Sketchpad, you can view X(303).

X(303) lies on these lines:
2,6   3,622   5,621   13,99   15,316   17,76   62,630   140,634   264,301   300,311   317,471   381,617   549,616

X(303) = isotomic conjugate of X(18)
X(303) = X(300)-Ceva conjugate of X(298)
X(303) = X(62)-cross conjugate of X(472)


X(304) = ISOTOMIC CONJUGATE OF X(19)

Trilinears       (cot A)csc2A : (cot B)csc2B : (cot C)csc2C
                        = cos A csc(A - ω) : cos B csc(B - ω) : cos C csc(C - ω)

Barycentrics  (cos A)csc2A : (cos B)csc2B : (cos C)csc2C

X(304) lies on these lines:
1,75   8,3263   63,1102   69,72   76,85   92,561   255,293   279,346   305,306   309,322   337,1565   341,668   345,348   662,2172   742,2176   799,2349   811,1895   1921,3061   1958,1973

X(304) = isogonal conjugate of X(1973)
X(304) = isotomic conjugate of X(19)
X(304) = cevapoint of X(I) and X(J) for these (I,J): (63,326), (69,345), (312,322)
X(304) = X(I)-cross conjugate of X(J) for these (I,J): (63,75), (306,69)


X(305) = ISOTOMIC CONJUGATE OF X(25)

Trilinears       b4c4cos A : c4a4cos B : a4b4cos C
                        = cot A csc(A - ω) : cot B csc(B - ω) : cot C csc(C - ω)

Barycentrics  b3c3cos A : c3a3cos B : a3b3cos C

X(305) = trilinear-pole-of-line-X(525)X(3267) = pole-with-respect-to-polar-circle-of trilinear-polar-of-X(2207) = X(48)-isoconjugate-of-X(2207) = X(92)-isoconjugate-of-X(1501)    Randy Hutson, August 15, 2013

X(305) lies on these lines:
2,39   22,99   25,683   95,183   264,325   287,394   304,306   311,1007   341,1088   350,614   561,1441

X(305) = isogonal conjugate of X(1974)
X(305) = isotomic conjugate of X(25)
X(305) = anticomplement of X(1196)
X(305) = X(I)-cross conjugate of X(J) for these (I,J): (69,76), (339, (3267)
X(305) = cevapont of X(339) and X(3267)


X(306) = ISOTOMIC CONJUGATE OF X(27)

Trilinears       (b2c2)(b + c)cos A : (c2a2)(c + a)cos B : (a2b2)(a + b)cos C
Barycentrics  bc(b + c)cos A : ca(c + a)cos B : ab(a + b)cos C

X(306) lies on these lines:
1,2   27,1043   63,69   72,440   92,264   209,518   226,321   253,329   287,293   304,305   319,333

X(306) = isogonal conjugate of X(1474)
X(306) = isotomic conjugate of X(27)
X(306) = complement of X(3187)
X(306) = X(I)-Ceva conjugate of X(J) for these (I,J): (69, 72), (312,321), (313,10)
X(306) = X(I)-cross conjugate of X(J) for these (I,J): (71,10), (72,307), (440,2)
X(306) = crosspoint of X(I) and X(J) for these (I,J): (69,304), (312,345)
X(306) = crosssum of X(604) and X(608)


X(307) = ISOTOMIC CONJUGATE OF X(29)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = b2c2(b + c)(cos A)/(b + c - a)
Barycentrics  af(a,b,c) : bf(b,c,a) :cf(c,a,b)

X(307) lies on these lines: 2,7   8,253   69,73   75,225   86,283   95,320   141,241   269,936   319,664   948,966

X(307) = isogonal conjugate of X(2299)
X(307) = isotomic conjugate of X(29)
X(307) = X(349)-Ceva conjugate of X(226)
X(307) = X(I)-cross conjugate of X(J) for these (I,J): (72,306), (73,226)
X(307) = crosspoint of X(69) and X(75)
X(307) = crosssum of X(25) and X(31)


X(308) = ISOTOMIC CONJUGATE OF X(39)

Trilinears       b3c3/(b2 + c2) : c3a3/(c2 + a2) : a3b3/(a2 + b2)
                        = csc2A csc(A + ω) : csc2B csc(B + ω) : csc2C csc(C + ω)
                        = [csc(A - ω)]/(b2 + c2) : [csc(B - ω)]/(c2 + a2) : [csc(C - ω)]/(a2 + b2)

Barycentrics  (b2c2)/(b2 + c2) : (c2a2)/(c2 + a2) : (a2b2)/(a2 + b2)
                        = csc A csc(A + ω) : csc B csc(B + ω) : csc C csc(C + ω)

X(308) lies on these lines: 2,702   6,76   25,183   42,313   69,263   111,689   141,670   251,385   290,311

X(308) = isogonal conjugate of X(3051)
X(308) = isotomic conjugate of X(39)
X(308) = cevapoint of X(2) and X(76)
X(308) = X(I)-cross conjugate of X(J) for these (I,J): (2,83), (385,290)


X(309) = ISOTOMIC CONJUGATE OF X(40)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (csc2A)/(-1 - cos A + cos B + cos C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(309) lies on these lines: 69,189   75,280   77,318   84,314   85,264   304,322

X(309) = isogonal conjugate of X(2187)
X(309) = isotomic conjugate of X(40)
X(309) = cevapoint of X(189) and X(280)
X(309) = X(I)-cross conjugate of X(J) for these (I,J): (7,75), (92,85)


X(310) = ISOTOMIC CONJUGATE OF X(42)

Trilinears       b3c3/(b + c) : c3a3/(c + a) : a3b3/(a + b)
Barycentrics  b2c2/(b + c) : c2a2/(c + a) : a2b2/(a + b)

X(310) lies on these lines: 2,39   7,314   38,75   86,350   99,675   261,272   321,335   333,673   670,903   871,982

X(310) = isogonal conjugate of X(1918)
X(310) = isotomic conjugate of X(42)
X(310) = cevapoint of X(I) and X(J) for these (I,J): (75,76), (274,314)
X(310) = X(75)-cross conjugate of X(274)


X(311) = ISOTOMIC CONJUGATE OF X(54)

Trilinears       csc2A cos(B - C) : csc2B cos(C - A) : csc2C cos(A - B)
Barycentrics  csc A cos(B - C) : csc B cos(C - A) : csc C cos(A - B)

X(311) lies on these lines: 2,570   4,69   22,157   53,324   95,99   141,338   290,308   300,303   301,302   305,1007

X(311) = isotomic conjugate of X(54)
X(311) = anticomplement of X(570)
X(311) = X(76)-Ceva conjugate of X(343)
X(311) = cevapoint of X(5) and X(343)
X(311) = X(5)-cross conjugate of X(324)


X(312) = ISOTOMIC CONJUGATE OF X(57)

Trilinears       (b + c - a)b2c2 : (c + a - b)c2a2 : (a + b - c)a2b2
                        = (1 + cos A)csc(A - ω) : (1 + cos B)csc(B - ω) : (1 + cos C)csc(C - ω)

Trilinears       (csc A)/(1 - cos A) : (csc B)/(1 - cos B) : (csc C)/(1 - cos C)     (M. Iliev, 4/12/07)

Barycentrics  bc(b + c - a) : ca(c + a - b) : ab(a + b - c)

X(312) lies on these lines: 1,1089   2,37   8,210   9,314   29,33   63,190   69,189   76,85   92,264   212,643   223,664   726,982   894,940   975,1010

X(312) = isogonal conjugate of X(604)
X(312) = isotomic conjugate of X(57)
X(312) = complement of X(3210)
X(312) = X(I)-Ceva conjugate of X(J) for these (I,J): (76,75), (304,322), (314,8)
X(312) = cevapoint of X(I) and X(J) for these (I,J): (2,329), (8,346), (9,78), (306,321)
X(312) = X(I)-cross conjugate of X(J) for these (I,J): (8,75), (9,318), (306,345), (346,341)
X(312) = crosssum of X(I) and X(J) for these (I,J): (32,1397), (56,1403), (57,1424)


X(313) = ISOTOMIC CONJUGATE OF X(58)

Trilinears       (b + c)b3c3 : (c + a)c3a3 : (a + b)a3b3
                        = (b + c)csc(A - ω) : (c + a)csc(B - ω) : (a + b)csc(C - ω)

Barycentrics  (b + c)b2c2 : (c + a)c2a2 : (a + b)a2b2

X(313) lies on these lines: 10,75   12,349   42,308   71,190   80,314   92,264   321,594   561,696

X(313) = isogonal conjugate of X(2206)
X(313) = isotomic conjugate of X(58)
X(313) = X(76)-Ceva conjugate of X(321)
X(313) = cevapoint of X(10) and X(306)
X(313) = X(321)-cross conjugate of X(349)
X(313) = crosssum of X(32) and X(560)


X(314) = ISOTOMIC CONJUGATE OF X(65)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = b2c2(b + c - a)/(b + c)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = bc(b + c - a)/(b + c)

X(314) lies on these lines:
1,75   2,941   4,69   6,981   7,310   9,312   21,261   29,1039   58,987   79,320   80,313   81,321   84,309   99,104   256,350   294,645

X(314) = isogonal conjugate of X(1402)
X(314) = isotomic conjugate of X(65)
X(314) = anticomplement of X(2092)
X(314) = X(310)-Ceva conjugate of X(274)
X(314) = cevapoint of X(I) and X(J) for these (I,J): (8,312), (69,75)
X(314) = X(I)-cross conjugate of X(J) for these (I,J): (8,333), (69,332), (333,274), (497,29)


X(315) = ISOTOMIC CONJUGATE OF X(66)

Trilinears       bc(b4 + c4 - a4) : ca(c4 + a4 - b4) : ab(a4 + b4 - c4)
Barycentrics  b4 + c4 - a4 : c4 + a4 - b4 : a4 + b4 - c4

X(315) lies on these lines:
2,32   3,325   4,69   5,183   8,760   20,99   68,290   192,746   194,736   274,377   297,394   343,458   371,491   372,492   631,1007

X(315) = midpoint of X(637) and X(638)
X(315) = reflection of X(I) in X(J) for these (I,J): (32,626), (371,640, (372,639)
X(315) = isogonal conjugate of X(2353)
X(315) = isotomic conjugate of X(66)
X(315) = anticomplement of X(32)
X(315) = anticomplementary conjugate of X(194)
X(315) = X(I)-cross conjugate of X(J) for these (I,J): (206,2)


X(316) = DROUSSENT PIVOT

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc(b4 + c4 - a4 - b2c2)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = b4 + c4 - a4 - b2c2

The reflection of X(99) in the polar of X(76).

Lucien Droussent, "Cubiques circulaires anallagmatiques par points réciproques ou isogonaux," Mathesis 62 (1953) 204-215.

X(316) lies on these lines:
2,187   4,69   15,303   16,302   30,99   115,385   148,538   183,381   249,297   265,290   298,530   299,531   376,1007   384,626   512,850   524,671   691,858

X(316) = midpoint of X(621) and X(622) X(316) = reflection of X(I) in X(J) for these (I,J): (15,624), (16,623), (99,325), (385,115), (691,858)
X(316) = isogonal conjugate of X(3455)
X(316) = isotomic conjugate of X(67)
X(316) = anticomplement of X(187)
X(316) = crosssum of X(39) and X(187)


X(317) = ISOTOMIC CONJUGATE OF X(68)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sec A cos 2A csc2A
                        = bc cot 2A : ca cot 2B : ab cot 2C
Barycentrics   cot 2A : cot 2B : cot 2C
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = tan A cos 2A csc2A

X(317) lies on these lines:
2,95   4,69   6,297   25,325   53,524   66,290   141,458   183,427   193,393   261,406   273,320   298,473   299,472   302,470   303,471   318,319   459,1007

X(317) = isogonal conjugate of X(2351)
X(317) = isotomic conjugate of X(68)
X(317) = anticomplement of X(577)
X(317) = cevapoint of X(52) and X(467)


X(318) = ISOTOMIC CONJUGATE OF X(77)

Trilinears       (1 + sec A)/a2 : (1 + sec B)/b2 : (1 + sec C)/c2
                        = sec A csc2A/2 : sec B csc2B/2 : sec C csc2C/2

Barycentrics  (1 + sec A)/a : (1 + sec B)/b : (1 + sec C)/c

X(318) lies on these lines:
2,280   4,8   10,158   29,33   53,594   63,412   75,225   77,309   108,404   200,1089   208,653   239,458   243,958   253,342   281,346   317,319   475,1068

X(318) = isogonal conjugate of X(603)
X(318) = isotomic conjugate of X(77)
X(318) = X(264)-Ceva conjugate of X(92)
X(318) = cevapoint of X(9) and X(33)
X(318) = X(I)-cross conjugate of X(J) for these (I,J): (9,312), (10,8), (281,92)


X(319) = ISOTOMIC CONJUGATE OF X(79)

Trilinears       (1 + 2 cos A)/a2 : (1 + 2 cos B)/b2 : (1 + 2 cos C)/c2
Barycentrics  (1 + 2 cos A)/a : (1 + 2 cos B)/b : (1 + 2 cos C)/c

X(319) lies on these lines: 2,1100   7,8   10,86   80,313   141,239   171,757   200,326   261,502   298,1082   299,559   306,333   307,664   317,318   321,1029   344,391    524,594

X(319) = reflection of X(894) in X(594)
X(319) = isotomic conjugate of X(79)
X(319) = anticomplement of X(1100)


X(320) = ISOTOMIC CONJUGATE OF X(80)

Trilinears       (1 - 2 cos A)/a2 : (1 - 2 cos B)/b2 : (1 - 2 cos C)/c2
Barycentrics  (1 - 2 cos A)/a : (1 - 2 cos B)/b : (1 - 2 cos C)/c

X(320) lies on these lines:
1,752   2,44   7,8   58,86   79,314   95,307   141,894   144,344   190,527   239,524   269,326   273,317   334,660   350,513   369,3232   519,679

X(320) = reflection of X(239) in X(1086)
X(320) = isotomic conjugate of X(80)
X(320) = X(214)-cross conjugate of X(1)
X(320) = crosssum of X(42) and X(902)


X(321) = ISOTOMIC CONJUGATE OF X(81)

Trilinears       (b + c)b2c2 : (c + a)c2a2 : (a + b)a2b2
                        = a(b + c)csc(A - ω) : b(c + a)csc(B - ω) : c(a + b)csc(C - ω)

Barycentrics  bc(b + c) : ca(c + a) : ab(a + b)

X(321) lies on these lines:
1,964   2,37   4,8   10,756   38,726   76,561  81,314   83,213   98,100   190,333   226,306   310,335   313,594   319,1029   668,671   693,824

X(321) = reflection of X(42) in X(1215)
X(321) = isogonal conjugate of X(1333)
X(321) = isotomic conjugate of X(81)
X(321) = X(I)-Ceva conjugate of X(J) for (I,J) = (75,10), (76,313), (312,306)
X(321) = cevapoint of X(37) and X(72)
X(321) = X(442)-cross conjugate of X(264)
X(321) = crosspoint of X(I) and X(J) for these (I,J): (75,76), (313,349)
X(321) = crosssum of X(31) and X(32)
X(321) = crossdifference of every pair of points on line X(667)X(838)


X(322) = ISOTOMIC CONJUGATE OF X(84)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (-1 - cos A + cos B + cos C)csc2A
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (-1 - cos A + cos B + cos C)csc A

X(322) lies on these lines: 2,1108   7,8   78,273   92,264   227,347   253,341   286,1043   304,309   326,664

X(322) = isogonal conjugate of X(2208)
X(322) = isotomic conjugate of X(84)
X(322) = anticomplement of X(1108)
X(322) = X(304)-Ceva conjugate of X(312)
X(322) = X(347)-cross conjugate of X(75)


X(323) = ISOTOMIC CONJUGATE OF X(94)

Trilinears       sin 3A csc2A : sin 3B csc2B : sin 3C csc2C
Trilinears        g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = 4 sin A - 3 csc A
Barycentrics  sin 3A csc A : sin 3B csc B : sin 3C csc C

X(323) lies on these lines: 2,6   20,155   23,110   30,146   140,195   187,249   401,525

X(323) = reflection of X(23) in X(110)
X(323) = isogonal conjugate of X(1989)
X(323) = isotomic conjugate of X(94)
X(323) = anticomplement of X(3580)
X(323) = X(340)-Ceva conjugate of X(186)
X(323) = cevapoint of X(6) and X(399)
X(323) = X(50)-cross conjugate of X(186)
X(323) = crosssum of X(395) and X(396)
X(323) = crossdifference of every pair of points on line X(51)X(512)


X(324) = ISOTOMIC CONJUGATE OF X(97)

Trilinears       bc sec A cos(B - C) : ca sec B cos(C - A) : ab sec C cos(A - B)
Barycentrics  sec A cos(B - C) : sec B cos(C - A) : sec C cos(A - B)

X(324) lies on these lines: 2,216   4,52   53,311   94,275   110,436   143,565

X(324) = isotomic conjugate of X(97)
X(324) = X(264)-Ceva conjugate of X(5)
X(324) = cevapoint of X(I) and X(J) for these (I,J): (5,53), (52,216)
X(324) = X(5)-cross conjugate of X(311)


X(325) = X(2)-HIRST INVERSE OF X(69)

Trilinears       csc2A cos(A + ω) : csc2B cos(B + ω) : csc2C cos(C + ω)
                        = f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc(b4 + c4 - a2b2 - a2c2)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = b4 + c4 - a2b2 - a2c2

X(325) lies on these lines:
2,6   3,315   5,76   11,350   22,160   25,317   30,99   39,626   114,511   115,538   187,620   232,297   250,340   264,305   274,442   383,622   523,684   621,1080

X(325) = midpoint of X(I) and X(J) for these (I,J): (99,316), (298,299)
X(325) = reflection of X(I) in X(J) for these (I,J): (115,625), (187,620), (385,230), (1513,114)
X(325) = isogonal conjugate of X(1976)
X(325) = isotomic conjugate of X(98)
X(325) = complement of X(385)
X(325) = anticomplement of X(230)
X(325) = cevapoint of X(2) and X(147)
X(325) = X(I)-cross conjugate of X(J) for these (I,J): (114,2), (511,297)
X(325) = crossdifference of every pair of points on line X(32)X(512)
X(325) = X(2)-Hirst inverse of X(69)


X(326) = ISOTOMIC CONJUGATE OF X(158)

Trilinears       cot2A : cot2B : cot2C
Trilinears       b2 + c2 - S2 : c2 + a2 - S2 : a2 + b2 - S2
Barycentrics  csc A - sin A : csc B - sin B : csc C - sin C

X(326) lies on these lines: 1,75   48,63   69,73   200,319   255,1102   269,320   322,664   610,662

X(326) = isogonal conjugate of X(1096)
X(326) = isotomic conjugate of X(158)
X(326) = X(I)-Ceva conjugate of X(J) for these (I,J): (304,63), (332,69)
X(326) = X(255)-cross conjugate of X(63)


X(327) = ISOTOMIC CONJUGATE OF X(182)

Trilinears       csc2A sec(A - ω) : csc2B sec(B - ω) : csc2C sec(C - ω)
                        = sin A csc(2A - 2 ω): sin B csc(2B - 2 ω) : sin C csc(2C - 2 ω)

Barycentrics  csc A sec(A - ω) : csc B sec(B - ω) : csc C sec(C - ω)

X(327) lies on these lines: 2,290   4,276   5,76   53,141   69,263   95,160

X(327) = isotomic conjugate of X(182)


X(328) = ISOTOMIC CONJUGATE OF X(186)

Trilinears       cot A csc 3A : cot B csc 3B : cot C csc 3C
Barycentrics  cos A csc 3A : cos B csc 3B : cos C csc 3C

X(328) lies on these lines: 2,94   69,265   95,99

X(328) = isotomic conjugate of X(186)
X(328) = X(265)-cross conjugate of X(94)


X(329) = ISOTOMIC CONJUGATE OF X(189)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = ( -1 - cos A + cos B + cos C)(csc A)
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = -1 - cos A + cos B + cos C

X(329) = perspector of triangle ABC and the pedal triangle of X(1490)

X(329) lies on these lines:
1,452   2,7   4,8   20,78   55,1005   69,189   100,972   190,345   191,498   196,342   200,516   219,278   220,948   223,347   253,306   388,960   392,1056   394,651   405,999   497,518

X(329) = isogonal conjugate of X(1436)
X(329) = isotomic conjugate of X(189)
X(329) = cyclocevian conjugate of X(1034)
X(329) = anticomplement of X(57)
X(329) = anticomplementary conjugate of X(7)
X(329) = X(I)-Ceva conjugate of X(J) for (I,J) = (69,8), (312,2)
X(329) = X(I)-cross conjugate of X(J) for these (I,J): (40,347), (223,2)


X(330) = ISOTOMIC CONJUGATE OF X(192)

Trilinears       bc/(ab + ac - bc) : ca/(bc + ba - ca) : ab/(ca + cb - ab)
Barycentrics  1/(ab + ac - bc) : 1/(bc + ba - ca) : 1/(ca + cb - ab)

X(330) lies on these lines: 1,87   2,1107   8,291   56,385   57,239   76,1015   105,932   145,1002   193,959   257,982

X(330) = isogonal conjugate of X(2176)
X(330) = isotomic conjugate of X(192)
X(330) = X(87)-Ceva conjugate of X(2)
X(330) = X(75)-cross conjugate of X(2)


X(331) = ISOTOMIC CONJUGATE OF X(219)

Trilinears       sec2(A/2) csc(2A) : sec2(B/2) csc(2B) : sec2(C/2) csc(2C)
                        = (1 - sec A)csc(A - ω) : (1 - sec B)csc(B - ω) : (1 - sec C)csc(C - ω)

Barycentrics  sec2(A/2) sec A : sec2(B/2) sec B : sec2(C/2) sec C

X(331) lies on these lines: 4,150   7,286   34,870   75,225   85,92   108,767   274,278

X(331) = isotomic conjugate of X(219)
X(331) = cevapoint of X(I) and X(J) for these (I,J): (7,278), (92,273)
X(331) = X(92)-cross conjugate of X(264)


X(332) = ISOTOMIC CONJUGATE OF X(225)

Trilinears       (cot A csc A)/(cos B + cos C) : (cot B csc B)/(cos C + cos A) : (cot C csc C)/(cos A + cos B)
Barycentrics  (cot A)/(cos B + cos C) : (cot B)/(cos C + cos A) : (cot C)/(cos A + cos B)

X(332) lies on these lines: 1,75   3,69   21,1036   99,102   219,345   261,284   1014,1037

X(332) = isotomic conjugate of X(225)
X(332) = cevapoint of X(I) and X(J) for these (I,J): (69,326), (78,345)
X(332) = X(I)-cross conjugate of X(J) for these (I,J): (69,314), (283,333)


X(333)  CEVAPOINT OF X(8) AND X(9)

Trilinears       bc(b + c - a)/(b + c) : ca(c + a - b)/(c + a) : ab(a + b - c)/(a + b)
Barycentrics  (b + c - a)/(b + c) : (c + a - b)/(c + a) : (a + b - c)/(a + b)

X(333) lies on these lines:
2,6   8,21   9,312   10,58   19,27   29,270   57,85   190,321   239,257   261,284   306,319   310,673   662,909   740,846   859,956   1021,1024

X(333) = isogonal conjugate of X(1400)
X(333) = isotomic conjugate of X(226)
X(333) = X(I)-Ceva conjugate of X(J) for these (I,J): (261,21), (274,86)
X(333) = cevapoint of X(I) and X(J) for these (I,J): (2,63), (8,9), (283,284)
X(333) = X(I)-cross conjugate of X(J) for these (I,J): (8,314), (9,21), (21,86), (283,332), (284,29)
X(333) = crosspoint of X(274) and X(314)
X(333) = crosssum of X(213) and X(1402)
X(333) = crossdifference of every pair of points on line X(512)X(810)


X(334) = ISOTOMIC CONJUGATE OF X(238)

Trilinears       b2c2/(a2 - bc) : c2a2/(b2 - ca) : a2b2/(c2 - ab)
Barycentrics  bc/(a2 - bc) : ca/(b2 - ca) : ab/(c2 - ab)

X(334) lies on these lines: 2,292   10,274   12,85   75,141   76,1089   150,295   320,660   741,839   767,813

X(334) = isogonal conjugate of X(2210)
X(334) = isotomic conjugate of X(238)
X(334) = X(75)-Hirst inverse of X(335)


X(335) = ISOTOMIC CONJUGATE OF X(239)

Trilinears       bc/(a2 - bc) : ca/(b2 - ca) : ab/(c2 - ab)
Barycentrics  1/(a2 - bc) : 1/(b2 - ca) : 1/(c2 - ab)

X(335) lies on these lines: 1,384   2,38   7,192   27,295   37,86   75,141   76,871   239,518   257,694   310,321   320,742   536,903   675,813   741,835   876,900

X(335) = reflection of X(I) in X(J) for these (I,J): (75,1086), (190,37)
X(335) = isogonal conjugate of X(1914)
X(335) = isotomic conjugate of X(239)
X(335) = cevapoint of X(I) and X(J) for these (I,J): (37,518), (292,295)
X(335) = X(I)-cross conjugate of X(J) for these (I,J): (295,337), (350,257)
X(335) = X(I)-Hirst inverse of X(J) for these (I,J): (2,291), (75,334), (292,894)


X(336) = ISOTOMIC CONJUGATE OF X(240)

Trilinears       csc A cot A sec(A + ω) : csc B cot B sec(B + ω) : csc C cot C sec(C + ω)
Barycentrics  cot A sec(A + ω) : cot B sec(B + ω) : cot C sec(C + ω)

X(336) lies on these lines: 1,811   48,75   73,290   255,293

X(336) = isotomic conjugate of X(240)


X(337) = ISOTOMIC CONJUGATE OF X(242)

Trilinears       (csc A cot A)/(a2 - bc) : (csc B cot B)/(b2 - ca) : (csc C cot C)/(c2 - ab)
Barycentrics  (cot A)/(a2 - bc) : (cot B)/(b2 - ca) : (cot C)/(c2 - ab)

X(337) lies on these lines: 12,85   37,86   72,295   201,348   291,986

X(337) = isotomic conjugate of X(242)
X(337) = X(295)-cross conjugate of X(335)


X(338)  CEVAPOINT OF X(115) AND X(125)

Trilinears       (b2 - c2)2/a3 : (c2 - a2)2/b3 : (a2 - b2)2/c3
                        = csc A sin2(B - C) : csc B sin2(C - A) : csc C sin2(A - B)

Barycentrics  (b2 - c2)2/a2 : (c2 - a2)2/b2 : (a2 - b2)2/c2
                        = sin2(B - C) : sin2(C - A) : sin2(A - B)

X(338) lies on these lines:
2,94   4,67   6,264   50,401   76,599   115,127   125,136   141,311

X(338) = isotomic conjugate of X(249)
X(338) = X(264)-Ceva conjugate of X(523)
X(338) = cevapoint of X(115) and X(125)
X(338) = X(125)-cross conjugate of X(339)


X(339) = ISOTOMIC CONJUGATE OF X(250)

Trilinears       (b2 - c2)2(cos A)/a4 : (c2 - a2)2(cos B)/b4 : (a2 - b2)2(cos C)/c4
                        = csc A cot A sin2(B - C) : csc B cot B sin2(C - A) : csc C cot C sin2(A - B)

Barycentrics  (b2 - c2)2(cos A)/a3 : (c2 - a2)2(cos B)/b3 : (a2 - b2)2(cos C)/c3
                        = cot A sin2(B - C) : cot B sin2(C - A) : cot C sin2(A - B)

X(339) lies on the MacBeath inconic and these lines: 3,76   69,265   115,127   264,381

X(339) = isotomic conjugate of X(250)
X(339) = X(I)-Ceva conjugate of X(J) for these (I,J): (76,525), (305,3267)
X(339) = X(125)-cross conjugate of X(338)
X(339) = crosspoint of X(305) and X(3267)


X(340) = ISOTOMIC CONJUGATE OF X(265)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = sec A sin 3A csc3A

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where
                        g(A,B,C) = sec A sin 3A csc2A

X(340) lies on these lines: 4,69   67,290   95,140   250,325   297,524   298,470   299,471   447,540    458,599   520,850

X(340) = reflection of X(648) in X(297)
X(340) = isotomic conjugate of X(265)
X(340) = anticomplement of X(3284)
X(340) = cevapoint of X(186) and X(323)


X(341) = ISOTOMIC CONJUGATE OF X(269)

Trilinears       b2c2(b + c - a)2 : c2a2(c + a - b)2 : a2b2(a + b - c)2
                        = csc4A/2 : csc4B/2 : csc4C/2

Barycentrics  bc(b + c - a)2 : ca(c + a - b)2 : ab(a + b - c)2

X(341) lies on these lines: 1,1050   8,210   10,75   40,190   200,1043   253,322   280,345   304,668   305,1088

X(341) = isogonal conjugate of X(1106)
X(341) = isotomic conjugate of X(269)
X(341) = X(346)-cross conjugate of X(312)


X(342) = ISOTOMIC CONJUGATE OF X(271)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (csc 2A tan A/2)(1 + cos A - cos B - cos C)
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sec A tan A/2)(1 + cos A - cos B - cos C)

X(342) lies on these lines: 4,7   9,653   85,264   92,226   108,1005   196,329   253,318   393,948

X(342) = isogonal conjugate of X(2188)
X(342) = isotomic conjugate of X(271)
X(342) = X(I)-Ceva conjugate of X(J) for these (I,J): (85,92), (264,273)
X(342) = cevapoint of X(208) and X(223)


X(343) = ISOTOMIC CONJUGATE OF X(275)

Trilinears       cot A cos(B - C) : cot B cos(C - A) : cot C cos(A - B)
Barycentrics  cos A cos(B - C) : cos B cos(C - A) : cos C cos(A - B)

X(343) lies on these lines:
2,6   3,68   5,51   22,161   53,311   76,297   140,569   315,458   427,511   470,634   471,633   472,621   473,622

X(343) = isotomic conjugate of X(275)
X(343) = complement of X(1993)
X(343) = X(I)-Ceva conjugate of X(J) for these (I,J): (76,311), (311,5)
X(343) = X(216)-cross conjugate of X(5)
X(343) = crosspoint of X(69) and X(76)
X(343) = crosssum of X(I) and X(J) for these (I,J): (6,571), (25,32)


X(344) = ISOTOMIC CONJUGATE OF X(277)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = (csc2A/2)[cos4(B/2) + cos4(C/2) - cos4(A/2)]

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A)f(A,B,C)

X(344) lies on these lines:
2,37   7,190   8,480   9,69   44,193   45,141   144,320   264,281   319,391

X(344) = isotomic conjugate of X(277)


X(345) = ISOTOMIC CONJUGATE OF X(278)

Trilinears       (csc A)/(1 - sec A) : (csc B)/(1 - sec B) : (csc C)/(1 - sec C)
                        = bc(b + c - a)(b2 + c2 - a2) : ca(c + a - b)(c2 + a2 - b2) : ab(a + b - c)(a2 + b2 - c2)

Barycentrics  1/(1 - sec A) : 1/(1 - sec B) : 1/(1 - sec C)

X(345) lies on these lines:
2,37   8,21   22,100   57,728   63,69   78,1040   190,329   219,332   280,341   304,348   498,1089

X(345) = isogonal conjugate of X(608)
X(345) = isotomic conjugate of X(278)
X(345) = X(I)-Ceva conjugate of X(J) for these (I,J): (304,69), (332,78)
X(345) = X(I)-cross conjugate of X(J) for these (I,J): (78,69), (219,8), (306,312)


X(346) = ISOTOMIC CONJUGATE OF X(279)

Trilinears       bc(b + c - a)2 : ca(c + a - b)2 : ab(a + b - c)2
                        = cos(A/2) csc3(A/2) : cos(B/2) csc3(B/2) : cos(C/2) csc3(C/2)

Barycentrics  (b + c - a)2 : (c + a - b)2 : (a + b - c)2

The cevian triangle of X(346) is perspective to the Ayme triangle; see X(3610).

X(346) lies on these lines:
2,37   6,145   8,9   45,594   69,144   78,280   100,198   219,644   220,1043   253,306   279,304   281,318   573,1018

X(346) = isogonal conjugate of X(1407)
X(346) = isotomic conjugate of X(279)
X(346) = X(312)-Ceva conjugate of X(8)
X(346) = X(200)-cross conjugate of X(8)
X(346) = crosspoint of X(312) and X(341)
X(346) = crosssum of X(604) and X(1106)


X(347) = ISOTOMIC CONJUGATE OF X(280)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (-1 - cos A + cos B + cos C) sec2(A/2)
Barycentrics  af(A,B,C) : bf(B,C,A) : cf(C,A,B)

X(347) lies on these lines:
1,7   2,92   8,253   34,452   37,948   69,664   75,280   144,219   223,329   227,322   241,1108   573,1020

X(347) = isogonal conjugate of X(2192)
X(347) = isotomic conjugate of X(280)
X(347) = anticomplement of X(281)
X(347) = X(I)-Ceva conjugate of X(J) for these (I,J): (75,7), (348,2)
X(347) = cevapoint of X(40) and X(223)
X(347) = X(I)-cross conjugate of X(J) for these (I,J): (40,329), (221,196), (227,223)
X(347) = crosspoint of X(75) and X(322)


X(348) = ISOTOMIC CONJUGATE OF X(281)

Trilinears       cot A sec2(A/2) : cot B sec2(B/2) : cot C sec2(C/2)
                        = (csc A)/(1 + sec A) : (csc B)/(1 + sec B) : (csc C)/(1 + sec C)

Barycentrics  1/(1 + sec A) : 1/(1 + sec B) : 1/(1 + sec C)

X(348) lies on these lines: 2,85   7,21   8,664   69,73   75,280   150,944   201,337   274,278   304,345   499,1111

X(348) = isogonal conjugate of X(607)
X(348) = isotomic conjugate of X(281)
X(348) = X(274)-Ceva conjugate of X(85)
X(348) = cevapoint of X(I) and X(J) for these (I,J): (2,347), (63,77)
X(348) = X(222)-cross conjugate of X(7)


X(349) = ISOTOMIC CONJUGATE OF X(284)

Trilinears       (cos B + cos C)csc3A : (cos C + cos A)csc3B : (cos A + cos B) csc3C
                        = (cos B + cos C)csc(A - ω) : (cos C + cos A)csc(B - ω) : (cos A + cos B)csc(C - ω)

Barycentrics  (cos B + cos C)csc2A : (cos C + cos A)csc2B : (cos A + cos B)(csc C/2)2

X(349) lies on these lines: 12,313   73,290   75,225   76,85

X(349) = isotomic conjugate of X(284)
X(349) = cevapoint of X(226) and X(307)
X(349) = X(321)-cross conjugate of X(313)


X(350) = X(2)-HIRST INVERSE OF X(75)

Trilinears       (a2 - bc)b2c2 : (b2 - ca)c2a2 : (c2 - ab)a2b2
Barycentrics  bc(a2 - bc) : ca(b2 - ca) : ab(c2 - ab)

X(350) is the perspector of triangle ABC and the tangential triangle of the conic that passes through A, B, C, and the pair P(10) and U(10) of bicentric points (see the notes just before X(1908). (Randy Hutson, 9/23/2011)

X(350) lies on these lines:
1,76   2,37   11,325   33,264   36,99   42,308   55,183   69,497   86,310   172,384   190,672   256,314   291,726   305,614   320,513   447,811   519,668   538,1015   889,903

X(350) = isogonal conjugate of X(1911)
X(350) = isotomic conjugate of X(291)
X(350) = crosspoint of X(257) and X(335)
X(350) = crossdifference of every pair of points on line X(213)X(667)
X(350) = X(2)-Hirst inverse of X(75)


X(351) = CENTER OF THE PARRY CIRCLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a(b2 - c2)(b2 + c2 - 2a2)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = a2(b2 - c2)(b2 + c2 - 2a2)

X(351) is the center of the Parry circle introduced in TCCT (Art. 8.13) as the circle that passes through X(I) for I = 2, 15, 16, 23, 110, 111, 352, 353.

X(351) lies on these lines: 2,804   110,526   184,686   187,237   694,881   865,888
X(351) = isogonal conjugate of X(892)
X(351) = crosspoint of X(110) and X(111)
X(351) = crosssum of X(I) and X(J) for these (I,J): (2,690), (523,524), (850,1236)
X(351) = crossdifference of every pair of points on line X(2)X(99)


X(352) = INVERSE-IN-CIRCUMCIRCLE OF X(353)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a(-a4 - b4 - c4 - 5b2c2 + 4a2b2 + 4a2c2)
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

A point on the Parry circle; see X(351).

X(352) lies on these lines: 2,6   3,353   110,187   111,511

X(352) = reflection of X(843) in X(187)
X(352) = inverse-in-circumcircle of X(353)
X(352) = crossdifference of every pair of points on line X(373)X(512)


X(353) = INVERSE-IN-BROCARD-CIRCLE OF X(111)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a(4a4 - 2b4 - 2c4 - b2c2 - 4a2b2 - 4a2c2)
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

A point on the Parry circle; see X(351).

X(353) lies on these lines: 3,352   6,23   110,574   111,182

X(353) = inverse-in-circumcircle of X(352)
X(353) = inverse-in-Brocard-circle of X(111)


X(354) = WEILL POINT

Trilinears       (b - c)2 - ab - ac : (c - a)2 - bc - ba : (a - b)2 - ca - cb
                        = 2 + cos B + cos C : 2 + cos C + cos A : 2 + cos A + cos B

Barycentrics  a[(b - c)2 - ab - ac] : b[(c - a)2 - bc - ba] : c[(a - b)2 - ca - cb]

X(354) is the centroid of the intouch triangle.

X(354) is the perspector of the intangents triangle and the triangle QAQBQC described at X(3598). (Peter Moses, Nov. 4, 2010)

William Gallatly, The Modern Geometry of the Triangle, 2nd edition, Hodgson, London, 1913, page 16.

X(354) lies on these lines: 1,3   2,210   6,374   7,479   11,118   37,38   42,244   44,748   48,584   63,1001   81,105   278,955   373,375   388,938   392,551   516,553

X(354) = isogonal conjugate of X(2346)
X(354) = inverse-in-incircle of X(1155)
X(354) = reflection of X(I) in X(J) for these (I,J): (210,2), (392,551)
X(354) = X(101)-Ceva conjugate of X(513)
X(354) = crosspoint of X(1) and X(7)
X(354) = crosssum of X(1) and X(55)


X(355) = FUHRMANN CENTER

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a cos A - (b + c)cos(B - C)

Trilinears       g(a,b,c) : g(b,c,a) : g(c,a,b),
                        where g(a,b,c) = bc(b + c)[a2(b2 + c2) - (b2 - c2)2] - a3bc(b2 + c2 - a2) (Michel Garitte, 4/3/03)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(355) = the center of the Fuhrmann circle, defined as the circumcircle of the Fuhrmann triangle A"B"C", where A" is obtained as follows: let A' be the midpoint of the circumcircle-arc having endpoints B and C and not containing A; then A" is the reflection of A' in line BC. Vertices B" and C" are obtained cyclically. (Other constructions of A'', and hence the Fuhrmann triangle, follow: (1) Let IA be the reflection of X(1) in BC; then A'' is the circumcenter of IABC. (2) Let JA be the reflection of the A-excenter in BC; then A'' is the circumcenter of JABC.

Ross Honsberger, Episodes in Nineteenth and Twentieth Century Euclidean Geometry, Mathematical Association of America, 1995. Chapter 6: The Fuhrmann Circle.

X(355) lies on these lines:
1,5   2,944   3,10   4,8   30,40   65,68   85,150   104,404   165,550   381,519   382,516   388,942   938,1056

X(355) = midpoint of X(4) and X(8)
X(355) = isogonal conjugate of X(3417)
X(355) = reflection of X(I) in X(J) for these (I,J): (1,5), (3,10), (944,1385), (1482,946)
X(355) = anticomplement of X(1385)
X(355) = complement of X(944)


X(356) = MORLEY CENTER

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = cos A/3 + 2 cos B/3 cos C/3
                        = g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = cos(B/3 - C/3) + sqrt(3)sin(A/3 + π/3) (M. Stevanovic, 12/25/2007)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(356) is the centroid of the Morley equilateral triangle. For a discussion of the theorem and extensive list of references, see

C. O. Oakley and J. C. Baker, "The Morley trisector theorem," American Mathematical Monthly 85 (1978) 737-745.

For a sketch of the Morley cubic and list of centers on it, including X(356), X(357), X(358), visit

Bernard Gibert's site.

If you have The Geometer's Sketchpad, you can view X(356).

For a biographical sketch, including details about Morley's famous theorem on angle trisectors, with history and references, see

Frank Morley (1860-1937) geometer.

X(356) lies on these lines: 357,358   1134,1135


X(357) = 1st MORLEY-TAYLOR-MARR CENTER

Trilinears       sec A/3 : sec B/3 : sec C/3
Barycentrics  sin A sec A/3 : sin B sec B/3 : sin C sec C/3

X(357) is the perspector of Morley triangle and ABC, and also the Hofstadter 1/3 point. See

F. Glanville Taylor and W. L. Marr, "The six trisectors of each of the angles of a triangle," Proceedings of the Edinburgh Mathematical Society 33 (1913-14) 119-131, especially item 9, page 127.

If you have The Geometer's Sketchpad, you can view X(357).

X(357) lies on these lines: 356,358   1134,3275

X(357) = isogonal conjugate of X(358)


X(358) = 2nd MORLEY-TAYLOR-MARR CENTER

Trilinears       cos A/3 : cos B/3 : cos C/3
Barycentrics  sin A cos A/3 : sin B cos B/3 : sin C cos C/3

X(358) is the perspector of the adjunct Morley triangle and ABC, and also the Hofstadter 2/3 point.

If you have The Geometer's Sketchpad, you can view X(358).

X(358) lies on these lines: 356,357   16,1135

X(358) = isogonal conjugate of X(357)


X(359) = HOFSTADTER ONE POINT

Trilinears       a/A : b/B : c/C
Barycentrics  a2/A : b2/B : c2/C

This point is the limit as r approaches 1 of the Hofstadter r point. See X(360) for details.

If you have The Geometer's Sketchpad, you can view X(359) and X(360) and Hofstadter Triangles. These sketches include the Hofstadter ellipse (actually a family of ellipses, indexed by a parameter r) introduced (February 4, 2005) by Peter J. C. Moses. The ellipse E(r) is given for 0 < r < 1 by the following equation in trilinears:

x2 + y2 + z2 + yz(D + 1/D) + zx(E + 1/E) + xy(F + 1/F) = 0,

where D = cos A - sin A cot rA, E = cos B - sin B cot rB, F = cos C - sin C cot rC.

The Hofstadter ellipse E(1/2), given by x2 + y2 + z2 - 2yz - 2xz - 2xy = 0, has center X(37) and passes through X(I) for these I: 244, 678, 2310, 2632, 2638, 2643, 4094.

Taking the limit of E(r) as r tends to 0 gives information about the circumellipse, E(0) (which is also E(1)):

Equation:     ayz/A + bzx/B + cxy/C = 0
Center:     X(5945) = (a/A)(b2/B + c2/C - a2/A) : (b/B)(c2/C + a2/A - b2/B) : (c/C)(a2/A + b2/B - c2/C)
Intersection with circumcircle (other than A, B, C):     X(3067) = a/[A(B - C)] : b/[B(C - A)] : c/[C(A - B)]

The ellipse E(1/2) is also the incentral inellipse, tangent to ABC at the traces of X(1); this ellipse is the incentral isotomic conjugate of the line X(512)X(4895). The perspector of the ellipse E(0) is X(359). (Randy Hutson, August 8, 2014)

See Hofstadter Ellipse at MathWorld.

X(359) = isogonal conjugate of X(360)
X(359) = X(2)-Ceva conjugate of X(5945)


X(360) = HOFSTADTER ZERO POINT

Trilinears       A/a : B/b : C/c
Barycentrics  A : B : C

This point is obtained as a limit of perspectors. Let r denote a real number, but not 0 or 1. Using vertex B as a pivot, swing line BC toward vertex A through angle rB and swing line BC about C through angle rC. Let A(r) be the point in which the two swung lines meet. Obtain B(r) and C(r) cyclically. Triangle A(r)B(r)C(r) is the r-Hofstadter triangle; its perspector with ABC, called the Hofstadter r point, is the point given by trilinears

(sin rA)/sin(A - rA) : (sin rB)/sin(B - rB) : (sin rC)/sin(C - rC).

The limit of this point as r approaches 0 is X(360). The two Hofstadter points, X(359) and X(360) are examples of transcendental triangle centers, since they have no trilinear or barycentric representation using only algebraic functions of a,b,c (or sin A, sin B, sin C).

Clark Kimberling, "Hofstadter points," Nieuw Archief voor Wiskunde 12 (1994) 109-114.

Conjecture and corollary (Randy Hutson, August 10, 2014)
If r is an integer other than 0, 1, or 2, then the inverse-in-circumcircle of the Hofstadter r point is the Hofstadter (2-r) point;
thus, since the isogonal conjugate of the Hofstadter r point is the Hofstadter (1-r) point, if r is not -1, 0 or 1,
then the antigonal image of the Hofstadter r point is the Hofstadter -r point.

X(1) = Hofstadter 1/2 point = antigonal image of X(80)
X(3) = Hofstadter 2 point = antigonal image of X(265)
X(4) = Hofstadter -1 point
X(35) = Hofstadter 3/2 point
X(79) = Hofstadter -1/2 point = antigonal image of X(3065)
X(186) = Hofstadter 3 point = antigonal image of X(5962)
X(265) = Hofstadter -2 point = antigonal image of X(3)
X(357) = Hofstadter 1/3 point
X(358) = Hofstadter 2/3 point
X(359) = Hofstadter 0 point
X(360) = Hofstadter 1 point
X(1127) = Hofstadter 1/4 point
X(1129) = Hofstadter 3/4 point
X(5457) = Hofstadter -1/3 point
X(5458) = Hofstadter -2/3 point
X(5961) = Hofstadter 4 point = antigonal image of X(5964)
X(5962) = Hofstadter -3 point = antigonal image of X(186)
X(5963) = Hofstadter 5 point X(5964) = Hofstadter -4 point = antigonal image of X(5961)

X(360) lies on the line 2,1115

X(360) = isogonal conjugate of X(359)
X(360) = anticomplement of X(1115)


X(361) = X(266)-CEVA CONJUGATE OF X(1)

Trilinears       csc B/2 + csc C/2 - csc A/2 : csc C/2 + csc A/2 - csc B/2 : csc A/2 + csc B/2 - csc C/2
Barycentrics  f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (sin A)(csc B/2 + csc C/2 - csc A/2)

The isoscelizer equation au(X) = bv(X) = cw(X) has solution X = X(361).

X(361) lies on these lines: 1,188   164,503   266,978

X(361) = X(266)-Ceva conjugate of X(1)


X(362) = CONGRUENT CIRCUMCIRCLES ISOSCELIZER POINT

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = b cos B/2 + c cos C/2 - a cos A/2

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

The isoscelizer equations u(X)/a = v(X)/b = w(X)/c have solution X = X(362).

If you have The Geometer's Sketchpad, you can view X(362).

X(362) lies on this line: 57,234


X(363) = EQUAL PERIMETERS ISOSCELIZER POINT

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = b/(1 + sin B/2) + c/(1 + sin C/2) - a/(1 + sin A/2)
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

When X = X(363), the isoscelizer triangles have equal perimeters.

X(363) is the homothetic center of the excentral triangle and the inner Hutson triangle. A construction of the latter follows. The internal bisector of angle A meets the A-excircle in two points. Let PA be the point closer to line BC and let QA be the other point. Define PB and PC cyclically, and define QB and QC cyclically. Let LA be the line tangent to the A-excircle at PA, and define LB and LC cyclically. Let MA be the line tangent to the A-excircle at QA, and define MB and MC cyclically. The inner Hutson triangle is the triangle A'B'C' given by A' = LB∩LC, B' = LC∩LA, C' = LA∩LB; the outer Hutson triangle is given by A'' = MB∩MC, B'' = MC∩MA, C' = MA∩MB. (Based on a description of A'B'C' by Randy Hutson, Sepember 23, 2011)

Peter Moses (November 10, 2011) found trilinears for A'B'C' and A''B''C''. As these are central triangles, trilinears for A' and A'' suffice:

A' = aUA(a2 + b2 + c2 - 2bc - 2ca - 2ab) + bUB(b + c - a)(c + a - b) + cUC(b + c - a)(a + b - c)
     : aUA(a2 + b2 - 3c2 + 2bc + 2ca - 2ab) + UB(c - a)(-a + b + c)(a - b + c) - cUC(-a + b + c)(a + b - c)
     : aUA(a2 - 3b2 + c2 + 2bc - 2ca + 2ab) + bUB(-a + b + c)(a - b + c) - UC(b - a)(-a + b + c)(a + b - c)

A'' = aUA(a2 + b2 + c2 - 2bc - 2ca - 2ab) - bUB(b + c - a)(c + a - b) - cUC(b + c - a)(a + b - c)
     : aUA(a2 + b2 - 3c2 + 2bc + 2ca - 2ab) - UB(c - a)(-a + b + c)(a - b + c) + cUC(-a + b + c)(a + b - c)
     : aUA(a2 - 3b2 + c2 + 2bc - 2ca + 2ab) - bUB(-a + b + c)(a - b + c) + UC(b - a)(-a + b + c)(a + b - c),

where UA = sqrt[bc/((a - b + c)(a + b - c)] = (1/2)csc(A/2), and UB and UC are defined cyclically.

A'B'C' is perspective to the following triangles: intouch, hexyl, Yff, circum-mid-arc, and the 1st and 2nd circumperp triangles. A''B''C'' is perspective to these: ABC, intouch, hexyl, Yff, circum-mid-arc, and the 1st and 2nd circumperp triangles. A'B'C' is homothetic to A''B''C'', which is perspective to the excentral triangle at X(168). (Peter Moses, 11/10/11)

If you have The Geometer's Sketchpad, you can view X(363).

X(363) lies on these lines: 1,289   40,164   165,166


X(364) = WABASH CENTER (EQUAL AREAS ISOSCELIZER POINT)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = b1/2 + c1/2 - a1/2
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

When X = X(364), the isoscelizer triangles T(X,a), T(X,b), T(X,c) have equal areas.

If you have The Geometer's Sketchpad, you can view X(364).

X(364) lies on these lines: 1,365   9,366

X(364) = X(366)-Ceva conjugate of X(1)


X(365) = SQUARE ROOT POINT

Trilinears       a1/2 : b1/2 : c1/2
Barycentrics  a3/2 : b3/2 : c3/2

For a construction of X(365), see the note at X(2), which provides for a construction barycentric square roots which one can easily extend to a construction for trilinear square roots.

X(365) lies on these lines: 1,364   6,2118   43,2068   292,2146   2110,2119   2144,2147

X(365) = isogonal conjugate of X(366)
X(365) = crosssum of X(1) and X(364)


X(366) = ISOGONAL CONJUGATE OF X(365)

Trilinears       a-1/2 : b-1/2 : c-1/2
Barycentrics  a1/2 : b1/2 : c1/2

See the note at X(365).

X(366) lies on these lines: 2,367   6,2068   9,364

X(366) = isogonal conjugate of X(365)
X(366) = cevapoint of X(1) and X(364)
X(366) = X(367)-cross conjugate of X(1)


X(367) = CROSSPOINT OF X(1) and X(366)

Trilinears       b1/2 + c1/2 : c1/2 + a1/2 : a1/2 + b1/2
Barycentrics  a(b1/2 + c1/2) : b(c1/2 + a1/2) : c(a1/2 + b1/2)

X(367) lies on these lines: 1,364   2,366

X(367) = crosspoint of X(1) and X(366)
X(367) = crosssum of X(1) and X(365)


X(368) = EQUI-BROCARD CENTER

Trilinears       (reasonable trilinears are sought)
Barycentrics  (reasonable barycentrics are sought)

The center X for which the triangle XBC, XCA, XAB have equal Brocard angles. Peter Yff proved that X(368) lies on the self-isogonal conjugate cubic with trilinear equation f(a,b,c)u + f(b,c,a)v + f(c,a,b)w = 0, where f(a,b,c) = bc(b2 - c2) and, for variable x : y : z, the cubics u, v, w are given by u(x,y,z) = x(y2 + z2), v = u(y,z,x), w = u(z,x,y).

Cyril Parry proved that X(368) lies on the anticomplement of the Kiepert hyperbola, this anticomplement being given by the trilinear equation a2(b2 - c2)x2 + b2(c2 - a2)y2 + c2(a2 - b2)z2 = 0.

If you have The Geometer's Sketchpad, you can view X(368) and X(368) With Curves.


X(369) = 1st TRISECTED PERIMETER POINT

Trilinears       x : y : z (see below)
Barycentrics  ax : by : cz

If you have The Geometer's Sketchpad, you can view X(369).

There exist points A', B', C' on segments BC, CA, AB, respectively, such that AB' + AC' = BC' + BA' = CA' + CB' = (a + b + c)/3, and the lines AA', BB', CC' concur in X(369). Near the end of the 20th century, Yff found trilinears for X(369) in terms of the unique real root, r, of the cubic polynomial

2t3 - 3(a + b + c)t2 + (a2 + b2 + c2 + 8bc + 8ca + 8ab)t - (cb2 + ac2 + ba2 + 5bc2 + 5ca2 + 5ab2 + 9abc),

as follows: x = bc(r - c + a)(r - a + b). Here x(a,c,b) ≠ x(a,b,c), so that y and z are not obtained from x by cyclically permutating a,b,c. At the geometry conference held at Miami University of Ohio, October 2, 2004, Yff, proved that X(369) is also given by x1 : y1 : z1 where y1 : z1 are given by cyclic permutations of a,b,c, in x1, where

x1 = bc[r2 - (2c + a)r + (- a2 + b2 + 2c2 + 2bc + 3ca + 2ab].

His presentation included a proof that there is only one point for which AB' + AC' = BC' + BA' = CA' + CB' .


X(370) = EQUILATERAL CEVIAN TRIANGLE POINT

Trilinears       (see below)
Barycentrics  (see below)

A point P is an equilateral cevian triangle point if the cevian triangle of P is equilateral. Jiang Huanxin introduced this notion in 1997.

Jean-Pierre Ehrmann notes (11/6/02) that the normalized barycentric coordinates (x,y,z) of X(370) are the unique solution of this system:

y(1 - y)SB + z(1 - z)SC = x(1 + x)F
z(1 - z)SC + x(1 - x)SA = y(1 + y)F
x(1 - x)SA + y(1 - y)SB = z(1 + z)F
x + y + z = 1,

where SA = (b2 + c2 - a2)/2; SB, SC are defined cyclically, F = [2 area(ABC)]/sqrt(3), and x>0, y>0, z>0.

Jiang Huanxin and David Goering, Problem 10358* and Solution, "Equilateral cevian triangles," American Mathematical Monthly 104 (1997) 567-570 [proposed 1994].

X(370) lies on the Neuberg cubic.


X(371) = KENMOTU POINT (CONGRUENT SQUARES POINT)

Trilinears       cos(A - π/4) : cos(B - π/4) : cos(C - π/4)
                        = cos A + sin A : cos B + sin B : cos C + sin C

Barycentrics  sin A cos(A - π/4) : sin B cos(B - π/4) : sin C cos(C - π/4)

There exist three congruent squares U, V, W positioned in ABC as follows: U has opposing vertices on segments AB and AC; V has opposing vertices on segments BC and BA; W has opposing vertices on segments CA and CB, and there is a single point common to U, V, W. The common point, X(371), may have first been published in Kenmotu's Collection of Sangaku Problems in 1840, indicating that its first appearance may have been anonymously inscribed on a wooden board hung up in a Japanese shrine or temple. (The Kenmotu configuration uses only half-squares; i.e., isosceles right triangles). Trilinears were found by John Rigby.

The edgelength of the three squares is 21/2abc/(a2 + b2 + c2 + 4σ), where σ = area(ABC). (Edward Brisse, 2/12/2000)

X(371) is the internal center of similitude of the circumcircle and the 2nd Lemoine circle (cosine circle) (Peter J. C. Moses, 5/9/03). Also, X(371) is the internal center of similitude of the Gallatly circle (defined just before X(2007)) and the 1st Lemoine circle (Peter J. C. Moses, 9/10/2003).

X(371) is the perspector of several pairs of triangles associated with Lucas circles. Some of these triangles are defined at MathWorld; e.g. Lucas Central Triangle, and others are Lucas(L:W) configurations. The latter are generalizations of configurations associated with Lucas circles, in which the squares are replaced by rectangles of length-to-width ratio L:W, with length on the corresponding sideline of ABC. A negative ratio indicates that the rectangles are directed inward; e.g. Lucas(-1:1) indicates inward-directed squares, whereas Lucas(1:1) indicates the classical case of outward-directed squares. These generalizations and the following properties of X(371) were contributed by Randy Hutson, 9/23/2011. See also X(372) and X(1084).

X(371) = perspector of ABC and the Lucas tangents triangle
X(371) = perspector of the Lucas central triangle and the anticevian triangle of X(6)
X(371) = perspector of the Lucas inner triangle and Lucas(-1:1) tangents triangle
X(371) = perspector of the Lucas(4:3) central triangle and the circumcevian triangle of X(6)
X(371) = perspector of the Lucas central triangle and the cevian triangle of X(588)
X(371) = radical center of the Lucas(2:1) circles
X(371) = X(481)-of-Lucas-central-triangle

Hidetoshi Fukagawa and John F. Rigby, Traditional Japanese Mathematics Problems of the 18th and 19th Centuries, SCT Publishing, Singapore, 2002. Reviewed, together with the Fukagawa and Pedoe book, Japanese Tempe Geometry Problems: San Gaku, by Clark Kimberling in The Mathematical Intelligencer 28, no. 1 (Winter 2006) 61-63.

Floor van Lamoen, Vierkanten in een driehoik: 3. Congruente vierkanten

Tony Rothman, with the cooperation of Hidetoshi Fukagawa, Japanese Temple Geometry (feature article in Scientific American)

If you have The Geometer's Sketchpad, you can view Kenmotu Point.

X(371) lies on these lines:
2,486   3,6   4,485   25,493   140,615   193,488   315,491   492,641   601,606   602,605

X(371) is the {X(3),X(6)}-harmonic conjugate of X(372). For a list of other harmonic conjugates of X(371), click Tables at the top of this page.

X(371) = reflection of X(I) in X(J) for these (I,J): (315,640), (372,32), (637,639)
X(371) = isogonal conjugate of X(485)
X(371) = inverse-in-Brocard-circle of X(372)
X(371) = inverse-in-1st-Lemoine-circle of X(2461)
X(371) = complement of X(637)
X(371) = anticomplement of X(639)
X(371) = X(4)-Ceva conjugate of X(372)


X(372) = {X(3),X(6)}-HARMONIC CONJUGATE OF X(371)

Trilinears       cos(A + π/4) : cos(B + π/4) : cos(C + π/4)
                        = cos A - sin A : cos B - sin B : cos C - sin C

Barycentrics  sin A cos(A + π/4) : sin B cos(B + π/4) : sin C cos(C + π/4)

X(372) is the external center of similitude of the circumcircle and the 2nd Lemoine circle (cosine circle) (Peter J. C. Moses, 5/9/03). Also, X(372) is the external center of similitude of the Gallatly circle (defined just before X(2007)) and the 1st Lemoine circle (Peter J. C. Moses, 9/10/03).

For details and references, see X(371).

Continuing from X(371) with properties of X(372) associated with Lucas circles:
X(372) = perspector of ABC and the Lucas(-1:1) tangents triangle
X(372) = perspector of ABC and the Lucas(-1:1) central triangle and anticevian triangle of X(6)
X(372) = perspector of the Lucas(-1:1) inner tangential triangle and the Lucas central triangle
X(372) = perspector of the Lucas(-4:3) central triangle and the circumcevian triangle of X(6)
X(372) = perspector of the Lucas(-1:1) central triangle and cevian triangle of X(589)
X(372) = radical center of the Lucas(-2:1) circles

If you have The Geometer's Sketchpad, you can view 2nd Kenmotu Point.

X(372) lies on these lines:
2,485   3,6   4,486   25,494   193,487   315,492   601,605   602,606

X(372) = reflection of X(I) in X(J) for these (I,J): (315,639), (371,32), (638,640)
X(372) = isogonal conjugate of X(486)
X(372) = inverse-in-Brocard-circle of X(371)
X(372) = inverse-in-1st-Lemoine-circle of X(2462)
X(372) = complement of X(638)
X(372) = anticomplement of X(640)
X(372) = X(4)-Ceva conjugate of X(371)


X(373) = CENTROID OF THE PEDAL TRIANGLE OF THE CENTROID

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 2bc + ac cos C + ab cos B
                        = g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = a(b4 + c4 - a2b2 - a2c2 - 6b2c2)

Barycentrics  h(a,b,c) : h(b,c,a) : h(c,a,b), where h(a,b,c) = 2abc + ca2cos C + ba2cos B

X(373) lies on these lines: 2,51   5,113   110,575   181,748   216,852   354,375

X(373) = crossdifference of every pair of points on line X(352)X(1499)


X(374) = CENTROID OF THE PEDAL TRIANGLE OF X(9)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 2b + 2c - 3a + (c + a)cos C + (b + a)cos B
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(374) lies on these lines: 6,354   9,517   44,65   51,210


X(375) = CENTROID OF THE PEDAL TRIANGLE OF X(10)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 2bc(b + c) + ca(c + a)cos C + ab(a + b)cos B
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(375) lies on these lines: 44,181   51,210   354,373

X(375) = midpoint of X(51) and X(210)


X(376) = CENTROID OF THE ANTIPEDAL TRIANGLE OF X(2)

Trilinears       5 cos A - cos(B - C) : 5 cos B - cos(C - A) : 5 cos C - cos(A - B)
                     = 2 cos A - cos B cos C : 2 cos B - cos C cos A : 2 cos C - cos A cos B
                     = 3 cos A - sin B sin C : 3 cos B - sin C sin A : 3 cos C - sin A sin B
                     = sec A - 2 sec B sec C : sec B - 2 sec C sec A : sec C - 2 sec A sec B
                      = f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (csc A)(5 sin 2A - sin 2B - sin 2C)

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = 5 sin 2A - sin 2B - sin 2C

X(376) = X(51)-of-hexyl-triangle.

X(376) lies on these lines:
1,553   2,3   35,388   36,497   40,519   55,1056   56,1058   69,74   98,543   103,544   104,528   110,541   112,577   165,515   316,1007   390,999   476,841   477,691   487,490   488,489   516,551

X(376) is the {X(3),X(20)}-harmonic conjugate of X(4). For a list of other harmonic conjugates of X(376), click Tables at the top of this page.

X(376) = midpoint of X(2) and X(20)
X(376) = reflection of X(I) in X(J) for these (I,J): (2,3), (4,2), (381,549)
X(376) = isogonal conjugate of X(3426)
X(376) = inverse-in-orthocentric-circle of X(3545)
X(376) = complement of X(3543)
X(376) = anticomplement of X(381)


X(377) = EULER LINE INTERCEPT OF LINE X(7)X(8)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc(b4 + c4 - a4 - 2b2c2 - 2abc(a + b + c))
                        = g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = cos A +(cos A + cos B + cos C) cos B cos C
Barycentrics  h(a,b,c) : h(b,c,a) : h(c,a,b), where h(a,b,c) = b4 + c4 - a4 - 2b2c2 - 2abc(a + b + c)

X(377) lies on these lines:
1,224   2,3   7,8   10,46   78,226   81,387   142,950   145,1056   149,1058   225,1038   274,315   908,936   1060,1068

X(377) is the {X(3),X(20)}-harmonic conjugate of X(21). For a list of other harmonic conjugates of X(377), click Tables at the top of this page.

X(377) = anticomplement of X(405)


X(378) = REFLECTION OF X(22) IN X(3)

Trilinears       sec A + 2 cos A : sec B + 2 cos B : sec C + 2 cos C
Barycentrics  tan A + sin 2A : tan B + sin 2B : tan C + sin 2C

X(378) lies on these lines:
1,1063   2,3   6,74   33,36   34,35   54,64   99,264   185,578   232,574   477,935   847,1105

X(378) is the {X(3),X(4)}-harmonic conjugate of X(24). For a list of other harmonic conjugates of X(378), click Tables at the top of this page.

X(378) = reflection of X(I) in X(J) for these (I,J): (4,427), (22,3)
X(378) = isogonal conjugate of X(4846)
X(378) = inverse-in-orthocentroidal-circle of X(403)


X(379) = EULER LINE INTERCEPT OF LINE X(6)X(7)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc[a5 + (b + c)(bca2 - (bc + ca + ab)(b - c)2)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = a5 + (b + c)(bca2 - (bc + ca + ab)(b - c)2)

X(379) lies on these lines: 2,3   6,7   41,226   63,169   264,823

X(379) = inverse-in-orthocentroidal-circle of X(857)
X(379) = crossdifference of every pair of points on line X(647)X(926)


X(380) = INTERSECTION OF LINES X(1)X(19) AND X(9)X(55)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (b + c - a)[3a3 + (b + c)(3a2 + (b - c)2 + a(b + c))]
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(380) lies on these lines: 1,19   6,40   9,55   165,579   223,608   281,950   282,1036


X(381) = MIDPOINT OF X(2) AND X(4)

Trilinears       2 cos(B - C) - cos A : 2 cos(C - A) - cos B : 2 cos(A - B) - cos C
                      = cos A + 4 cos B cos C : cos B + 4 cos C cos A : cos C + 4 cos A cos B

Barycentrics  a(cos A + 4 cos B cos C) : b(cos B + 4 cos C cos A) : c(cos C + 4 cos A cos B)

X(381) = center of the orthocentroidal circle
X(381) = centroid of the Euler triangle

Let A' be the reflection of X(3) in A, and define B'and C' cyclically. Let A'' be the reflection of X(3) in BC, and define B'' and C'' cyclically. The lines A'A'', B'B'', C'C'' concur in X(381).

X(381) lies on these lines:
2,3   6,13   11,999   49,578   51,568   54,156   98,598   114,543   118,544   119,528   125,541   127,133   155,195   183,316   184,567   210,517   262,671   264,339   298,622   299,621   302,616   303,617   355,519   388,496   495,497   511,599   515,551

X(381) is the {X(4),X(5)}-harmonic conjugate of X(3) and also the {X(13),X(14)}-harmonic conjugate of X(6). For a list of other harmonic conjugates of X(381), click Tables at the top of this page.

X(381) = midpoint of X(2) and X(4)
X(381) = reflection of X(I) in X(J) for these (I,J): (2,5), (3,2), (376,549), (549,547), (568,51), (3534,3)
X(381) = isogonal conjugate of X(3431)
X(381) = complement of X(376)
X(381) = anticomplement of X(549)
X(381) = crossdifference of every pair of points on line X(526)X(647)


X(382) = REFLECTION OF CIRCUMCENTER IN ORTHOCENTER

Trilinears       cos A - 4 cos B cos C : cos B - 4 cos C cos A : cos C - 4 cos A cos B
                     = 5 cos A - 4 sin B sin C : 5 cos B - 4 sin C sin A : 5 cos C - 4 sin A sin B
Barycentrics  a(cos A - 4 cos B cos C) : b(cos B - 4 cos C cos A) : c(cos C - 4 cos A cos B)

X(382) lies on these lines: 2,3   64,265   155,399   185,568   195,1498   355,516   952,962

X(382) is the {X(5),X(20)}-harmonic conjugate of X(3). For a list of other harmonic conjugates of X(382), click Tables at the top of this page.

X(382) = reflection of X(I) in X(J) for these (I,J): (3,4), (20,5), (110,1539), (550,546), (3534,381)
X(382) = inverse-in-orthocentroidal-circle of X(546)
X(382) = complement of X(3529)
X(382) = anticomplement of X(550)


X(383) = EULER LINE INTERCEPT OF LINE X(14)X(98)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = csc(B - C) [sin 2B cos(C - ω) sin(C + π/3) - sin 2C cos(B - ω) sin(B + π/3)]

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(383) lies on these lines: 2,3   13,262   14,98   183,621   299,511   325,622

X(383) = reflection of X(1080) in X(1513)
X(383) = inverse-in-orthocentroidal-circle of X(1080)


X(384) = EULER LINE INTERCEPT OF LINE X(32)X(76)

Trilinears       bc(a4 + b2c2) : ca(b4 + c2a2) : ab(c4 + a2b2)
Barycentrics  a4 + b2c2 : b4 + c2a2 : c4 + a2b2

A center on the Euler line; contributed by John Conway, email, 1998.

X(384) lies on these lines:
1,335   2,3   6,194   32,76   39,83   141,1031   172,350   185,287   316,626   694,695

X(384) = isogonal conjugate of X(695)
X(384) = X(694)-Ceva conjugate of X(385)
X(384) = eigencenter of cevian triangle of X(694)
X(384) = eigencenter of anticevian triangle of X(385)


X(385) = X(2)-HIRST INVERSE OF X(6)

Trilinears       bc(a4 - b2c2) : ca(b4 - c2a2) : ab(c4 - a2b2)
Barycentrics  a4 - b2c2 : b4 - c2a2 : c4 - a2b2

Contributed by John Horton Conway, 1998.

X(385) is the perspector of triangle ABC and the tangential triangle of the conic that passes through A, B, C, and the pair P(1) and U(1) of bicentric points (see the notes just before X(1908). (Randy Hutson, 9/23/2011)

X(385) lies on these lines:
1,257   2,6   3,194   23,523   30,148   32,76   55,192   56,330   98,511   99,187   111,892   115,316   171,894   232,648   248,290   251,308   262,576

X(385) = reflection of X(I) in X(J) for these (I,J): (99,187), (147,1513), (298,395), (299,396), (316,115), (325,230)
X(385) = isogonal conjugate of X(694)
X(385) = isotomic conjugate of X(1916)
X(385) = anticomplement of X(325)
X(385) = X(I)-Ceva conjugate of X(J) for these (I,J): (98,2), (511,401), (694,384)
X(385) = crosspoint of X(290) and X(308)
X(385) = crosssum of X(I) in X(J) for these (I,J): (141,698), (384,385)
X(385) = crossdifference of every pair of points on line X(39)X(512)
X(385) = X(I)-Hirst inverse of X(J) for these (I,J): (2,6), (3,194), (171,894)


X(386) = INVERSE-IN-BROCARD-CIRCLE OF X(58)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a(b2 + c2 + bc + ca + ab)

Trilinears        h(a,b,c) : h(b,c,a) : h(c,a,b), where h(a,b,c) = r cos A + s sin A, s = semiperimeter, r = inradius

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = a2(b2 + c2 + bc + ca + ab)

X(386) is the external center of similitude of the circumcircle and Apollonius circle. The internal center is X(573). (Peter J. C. Moses, 8/22/03)

X(386) lies on these lines:
1,2   3,6   31,35   40,1064   55,595   56,181   57,73   65,994   81,404   474,940   758,986   872,984

X(386) is the {X(3),X(6)}-harmonic conjugate of X(58). For a list of other harmonic conjugates of X(386), click Tables at the top of this page.

X(386) = inverse of X(58) in the Brocard circle
X(386) = crosssum of X(6) in X(1011)
X(386) = crossdifference of every pair of points on line X(523)X(649)


X(387) = INTERSECTION OF LINES X(1,2) AND X(4,6)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc[-a4 + 2a2(a + b + c)2 + (b2 - c2)2]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = -a4 + 2a2(a + b + c)2 + (b2 - c2)2

X(387) lies on these lines:
1,2   4,6   20,58   40,579   65,278   81,377   390,595   443,940

X(387) = crossdifference of every pair of points on line X(520)X(649)


X(388) = INTERSECTION OF LINES X(1)X(4) and X(7)X(8)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc[a2 + (b + c)2]/(b + c - a)
                        = 1 + cos B cos C : 1 + cos C cos A : 1 + cos A cos B
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = [a2 + (b + c)2]/(b + c - a)
X(388) = 2(R/r)*X(1) + 3X(2) - 2X(3)

X(388) lies on these lines:
1,4   2,12   3,495   5,999   7,8   10,57   11,153   20,55   29,1037   35,376   36,498   79,1000   108,406   171,603   201,984   329,960   354,938   355,942   381,496   442,956   452,1001   612,1038   750,1106   1059,1067

X(388) is the {X(7),X(8)}-harmonic conjugate of X(65). For a list of other harmonic conjugates of X(388), click Tables at the top of this page.

X(388) = isogonal conjugate of X(1036)
X(388) = anticomplement of X(958)


X(389) = CENTER OF THE TAYLOR CIRCLE

Trilinears       cos A - cos 2A cos(B - C) : cos B - cos 2B cos(C - A) : cos C - cos 2C cos(A - B)
Barycentrics  a[cos A - cos 2A cos(B - C)] : b[cos B - cos 2B cos(C - A)] : c[cos C - cos 2C cos(A - B)]

If ABC is acute then X(389) is the Spieker center of the orthic triangle. Peter Yff reports (Sept. 19, 2001) that since X(389) is on the Brocard axis, there must exist T for which X(389) is sin(A+T) : sin(B+T) : sin(C+T), and that tan(T) = - cot A cot B cot C.

Let HA be the A-altitude of triangle ABC, and let A' be the midpoint of segment AHA. Let LA be the line through A' parallel to AO, where O denotes the circumcenter. Define LB and LC cyclically. The lines LA, LB, LC concur in X(389). (Construction by Alexei Myakishev, March 24, 2010.)

Let OA be the circle with center A tangent to line BC, and define OB and OC cyclically. X(389) is the radical center of the three circles. (Randy Hutson, 9/23/2011)

Let A'B'C' be the orthic triangle, let A'' be the orthocenter of AB'C', and define B'' and C'' cyclically. The triangle A''B''C'' is homothetic to A'B'C', and the center of homothety is X(389). (Randy Hutson, 9/23/2011)

If you have The Geometer's Sketchpad, you can view X(389).

X(389) lies on these lines:
3,6   4,51   24,184   30,143   54,186   115,129   217,232   517,950

X(389) = midpoint of X(I) and X(J) for these (I,J): (3,52), (4,185), (974,1112)
X(389) = reflection of X(1216) in X(140)
X(389) = inverse-in-Brocard-circle of X(578)
X(389) = crosspoint of X(4) and X(54)
X(389) = crosssum of X(I) and X(J) for these (I,J): (3,5), (6,418)


X(390)  REFLECTION OF GERGONNE POINT IN INCENTER

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc(b + c - a)[3a2 + (b - c)2]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = (b + c - a)[3a2 + (b - c)2]
X(390) = 4(R/r)*X(1) - 3X(2) + 4X(3)

X(390) lies on these lines:
1,7   2,11   3,1058   4,495   8,9   30,1056   40,938   144,145   376,999   387,595   496,631   944,971   952,1000

X(390) = midpoint of X(144) and X(145)
X(390) = reflection of X(I) in X(J) for these (I,J): (7,1), (8,9)
X(390) = anticomplement of X(2550)
X(390) = crossdifference of every pair of points on line X(657)X(665)


X(391) = INTERSECTION OF LINES X(2,6) AND X(8,9)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc(3a + b + c)(b + c - a)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = (3a + b + c)(b + c - a)

X(391) lies on these lines:
2,6   8,9   20,573   37,145   75,144   319,344

X(391) is the {X(8),X(9)}-harmonic conjugate of X(346). For a list of other harmonic conjugates of X(391), click Tables at the top of this page.


X(392) = INTERSECTION OF LINES X(1,6) AND X(10,11)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (b + c)(b2 + c2 - a2) + 4abc
Barycentrics  af(a,b,c): bf(b,c,a): cf(c,a,b)

X(392) lies on these lines:
1,6   2,517   8,1000   10,11   21,104   40,474   55,997   63,999   78,1057   210,519   329,1056   354,551   442,946   443,962   452,944   495,908

X(392) = reflection of X(354) in X(551)


X(393) = X(25)-CROSS CONJUGATE OF X(4)

Trilinears       bc tan2A : ca tan2B : ab tan2C
                        = sec A - csc B csc C : sec B - csc C csc A : sec C - csc A csc B

Barycentrics  tan2A : tan2B : tan2C

X(393) lies on these lines:
1,836   2,216   4,6   19,208   20,577   24,254   25,1033   27,967   33,42   37,158   69,297   107,111   193,317   230,459   278,1108   342,948   394,837   800,1093

X(393) = crosspoint of X(4) and X(459)
X(393) = X(25)-cross conjugate of X(4)
X(393) = crosssum of X(577) and X(1092)


X(394) = X(69)-CEVA CONJUGATE OF X(3)

Trilinears       cos A cot A : cos B cot B : cos C cot C
Barycentrics  cos2A : cos2B : cos2C

X(394) lies on these lines: 2,6   3,49   20,1032   22,110   25,511   63,77   72,1060   76,275   78,271   287,305   297,315   329,651   393,837   399,541   470,633   471,634   472,622   473,621   611,612   613,614   1062,1069

X(394) = X(69)-Ceva conjugate of X(3)
X(394) = crosspoint of X(493) and X(494)
X(394) = crosssum of X(4) and X(459)
X(394) = crossdifference of every pair of points on line X(460)X(512)


X(395) = MIDPOINT OF X(14) AND X(16)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = cos(B - C) + 2 cos(A + π/3)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,B,A)

X(395) lies on these lines:
2,6   3,398   5,13   14,16   15,549   39,618   53,472   61,140   115,530   187,531   202,495   216,465   466,577   532,624   533,619

X(395) is the {X(2),X(6)}-harmonic conjugate of X(396). For a list of other harmonic conjugates of X(395), click Tables at the top of this page.

X(395) is the center of the (equilateral) pedal triangle of X(16), as well as the circumcenter of the pedal triangle of X(14).

X(395) = midpoint of X(I) and X(J) for these (I,J): (14,16), (298,385)
X(395) = reflection of X(396) in X(230)
X(395) = complement of X(299)
X(395) = crosspoint of X(2) and X(14)
X(395) = crosssum of X(6) and X(16)
X(395) = crossdifference of every pair of points on line X(15)X(512)


X(396) = MIDPOINT OF X(13) AND X(15)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = cos(B - C) + 2 cos(A - π/3)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,B,A)

X(396) lies on these lines:
2,6   3,397   5,14   13,15   16,549   39,619   53,473   62,140   115,531   187,530   203,495   216,466   465,577   532,618   533,623

X(396) is the {X(2),X(6)}-harmonic conjugate of X(395). For a list of other harmonic conjugates of X(396), click Tables at the top of this page.

X(396) is the center of the (equilateral) pedal triangle of X(15), as well as the circumcenter of the pedal triangle of X(13).

X(396) = midpoint of X(I) and X(J) for these (I,J): (13,15), (299,385)
X(396) = reflection of X(395) in X(230)
X(396) = isogonal conjugate of X(2981)
X(396) = anticomplement of X(298)
X(396) = crosspoint of X(2) and X(13)
X(396) = crosssum of X(6) and X(15)
X(396) = crossdifference of every pair of points on line X(16)X(512)


X(397)  CROSSPOINT OF X(4) AND X(17)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = cos(B - C) - 2 cos(A + π/3)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,B,A)

X(397) lies on these lines: 3,396   4,6   5,13   14,546   15,550   16,17   30,61   51,462   141,634   184,463   202,496   524,633   532,635

X(397) is the {X(4),X(6)}-harmonic conjugate of X(398). For a list of other harmonic conjugates of X(397), click Tables at the top of this page.

X(397) = crosspoint of X(4) and X(17)
X(397) = crosssum of X(3) and X(61)


X(398)  CROSSPOINT OF X(4) AND X(18)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = cos(B - C) - 2 cos(A - π/3)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,B,A)

X(398) lies on these lines:
3,395   4,6   5,14   13,546   15,18   16,550   30,62   51,463   141,633   184,462   203,496   524,634   533,636

X(398) is the {X(4),X(6)}-harmonic conjugate of X(397). For a list of other harmonic conjugates of X(398), click Tables at the top of this page.

> X(398) = crosspoint of X(4) and X(18)
X(398) = crosssum of X(3) and X(62)


X(399) = PARRY REFLECTION POINT

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = 5 cos A - 4 cos B cos C - 8 sin B sin C cos2A

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,B,A)

Let L, M, N be lines through A, B, C, respectively, parallel to the Euler line. Let L' be the reflection of L in sideline BC, let M' be the reflection of M in sideline CA, and let N' be the reflection of N in sideline AB. The lines L', M', N' concur in X(399), as proved in

Cyril Parry, Problem 10637, American Mathematical Monthly 105 (1998) 68.

In Cosmin Pohoata, "On the Parry reflection point," Forum Geometricorum 8 (2008), 43-48 (click

here for a pdf) the following is proved:

Let A' be the reflection of vertex A in line BC, and define B', C' cyclically. Let AtBtCt be the tangential triangle of ABC. The circumcircles of the triangles AtB'C', A'BtC', A'B'Ct concur in X(399). Moreover, the circumcircles of triangles A'BtCt, AtB'Ct, AtBtC' concur in a point Q which we shall call the Parry-Pohoata point. Barycentric coordinates for Q, of degree 22 in a,b,c, were found by J. F. Garcia Captitán (Hyacinthos #15827, Nov. 19, 2007) and are included in Pohoata's article. Pohoata notes that the point Q lies on the circumcircle of the points X(3), X(4), X(399).

Let I, IA, IB, IC, denote the incenter and excenters of ABC. Lawrence Evans (Hyacinthos #6878) found that the circumcircles of the triangles IA'IA, IB'IB, IC'C concur in X(399).

The Pohoata article includes a proof that the triangles A'IBIC, IAB'IC, IAIBC' also pass through X(399). Similar results involving the Fermat points, X(13) and X(14), are proved.

Pohoata reports that the following points are concyclic: X(13), X(16), X(110), X(399), X(1338), as are the points X(14), X(15), X(110), X(399), X(1337). Randy Hutson adds (Aug. 13, 2012) that the first of these circles also passes through X(2381), and the second, through X(2380).

X(399) is the point P on the line X(3)X(74) for which the P-Brocard triangle is perspective to ABC. (Randy Hutson, August 26, 2014)

X(399) lies on the Neuberg cubic and these lines:
1,3065   3,74   4,195   6,13   30,146   155,382   394,541   1337,3441   1338,3440   3466,3483

X(399) = isogonal conjugate of X(1138)
X(399) = reflection of X(I) in X(J) for these (I,J): (3,110), (74,1511), (265,113)
X(399) = X(I)-Ceva conjugate of X(J) for these (I,J): (30,3), (323,6)
X(399) = inverse-in-circumcircle of X(1511)
X(399) = tangential isogonal conjugate of X(2070)
X(399) = antigonal image of X(1117)


X(400) = YFF-MALFATTI POINT

Trilinears       csc4(A/4) : csc4(B/4) : csc4(C/4)
Barycentrics  sin A csc4(A/4) : sin B csc4(B/4) : sin C csc4(C/4)

In 1997, Yff considered the configuration for the 1st Ajima-Malfatti point, X(179). He proved that the same tangencies are possible in another way if the circles are not required to lie inside ABC. With tangency points labeled as before, the lines AA', BB', CC' concur in X(400).

If you have The Geometer's Sketchpad, you can view X(400).



leftri Centers 401- 475, rightri
2- 4, 20- 30, 376, 379, 381- 384 (and others) lie on the Euler line.

underbar

X(401) = BAILEY POINT

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where
                        f(A,B,C) = [sin 2B sin 2C - sin2(2A)](csc A)
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin 2B sin 2C - sin2(2A)

X(401) lies on these lines:
2,3   50,338   97,276   248,290   264,577  287,511   323,525

X(401) = reflection of X(297) in X(441)
X(401) = isogonal conjugate of X(1987)
X(401) = isotomic conjugate of X(1972)
X(401) = anticomplement of X(297)
X(401) = X(I)-Ceva conjugate of X(J) for these (I,J): (287,2), (511,385)
X(401) = crosspoint of X(276) and X(290)
X(401) = crosssum of X(217) and X(237)
X(401) = crossdifference of every pair of points on line X(51)X(647)
X(401) = X(2)-Hirst inverse of X(3)


X(402) = ZEEMAN-GOSSARD PERSPECTOR

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = p(a,b,c)y(a,b,c)/a, polynomials p and y as given below

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where
                        g(a,b,c) = p(a,b,c)y(a,b,c), polynomials p and y as given below

In A History of Mathematics, Florian Cajori wrote, "H. C. Gossard of the University of Oklahoma showed in 1916 that the three Euler lines of the triangles formed by the Euler line and the sides, taken by twos, of a given triangle, form a triangle . . . perspective with the given triangle and having the same Euler line." Let ABC be the given triangle and A'B'C' the Gossard triangle - that is, the triangle perspective with the given triangle and having the same Euler line. The lines AA', BB', CC' concur in X(402), named the Gosssard perspector by John Conway (1998).

Actually, X(402) dates back to an article by Christopher Zeeman in Wiskundige Opgaven 8 (1899-1902) 305. For details, see Paul Yiu's Hyacinthos message #7536 and others with Gossard in the subject line. (In ETC, the change of name from Gossard Perspector to Zeeman-Gossard Perspector was made on Oct. 15, 2003.) Further details are given by Wilson Stothers in Hyacinthos #8383, Oct. 21, 2003.

Barycentrics for X(402) were received from Paul Yiu (2/20/99); the polynomials p and y referred to above are given as follows:  

p(a,b,c) = 2a4 - a2b2 - a2c2 - (b2 - c2)2

y(a,b,c) = a8 - a6(b2 + c2) + a4(2b2 - c2)(2c2 - b2) + [(b2 - c2)2][3a2(b2 + c2) - b4 - c4 - 3b2c2]

X(402) lies on this line: 2,3

X(402) = complement of X(1650)


X(403) = X(36) OF THE ORTHIC TRIANGLE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (sec A)(1 + cos 2B + cos 2C)
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (tan A)(1 + cos 2B + cos 2C)

X(403) is centroid of the triangle having vertices X(4), P(4), U(4). (Regarding the bicentric pair P(4) and U(4), see the notes just before X(1908)). (Randy Hutson, 9/23/2011)

X(403) lies on these lines: 2,3   112,230   115,232   847,1093

X(403) = midpoint of X(4) and X(186)
X(403) = reflection of X(186) in X(468)
X(403) = inverse-in-circumcircle of X(24)
X(403) = inverse-in-nine-point-circle of X(4)
X(403) = inverse-in-orthocentroidal-circle of X(378)
X(403) = complement of X(2071)
X(403) = X(113)-cross conjugate of X(4)
X(403) = crossdifference of every pair of points on line X(577)X(647)


X(404) = {X(2),X(3)}-HARMONIC CONJUGATE OF X(21)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc(a + b + c) - a(b2 + c2 - a2)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = abc(a + b + c) - a2(b2 + c2 - a2)

X(404) lies on these lines:
1,88   2,3   8,56   10,36   31,978   46,997   57,78   60,662   63,936   69,1014   81,386   104,355   108,318   145,999   149,496   603,651   612,988   976,982

X(404) is the {X(2),X(3)}-harmonic conjugate of X(21). For a list of harmonic conjugates of X(404), click Tables at the top of this page.


X(405) = EULER LINE INTERCEPT OF LINE X(1)X(6)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc(a + b + c) + abc cos A
Trilinears       bcS + raSA : caS + rbSB : abS + rcSC)
Barycentrics  b + c + a(1 + cos A) : c + a + b(1 + cos B) : a + b + c(1 + cos C)

X(405) lies on these lines: 1,6   2,3   8,943   10,55   56,226   58,940   63,942   284,965   329,999   756,976   846,986

X(405) is the {X(2),X(3)}-harmonic conjugate of X(474). For a list of harmonic conjugates of X(405), click Tables at the top of this page.

X(405) = inverse-in-orthocentroidal circle of X(442)
X(405) = complement of X(377)
X(405) = crosssum of X(838) and X(1015)
X(405) = crossdifference of every pair of points on line X(513)X(647)


X(406) = EULER LINE INTERCEPT OF LINE X(10)X(33)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc(a + b + c) + abc sec A
Barycentrics  b + c + a(1 + sec A) : c + a + b(1 + sec B) : a + b + c(1 + sec C)

X(406) lies on these lines:
2,3   8,1061   10,33   37,158   92,1068   108,388   208,226   261,317

X(406) = inverse-in-orthocentroidal-circle of X(475)


X(407) = CROSSPOINT OF X(4) AND X(225)

Trilinears       (v + w)sec A : (w + u)sec B : (u + v)sec C, where
                        u : v : w = X(21); e.g., u = u(A,B,C) = 1/(cos B + cos C)

Barycentrics  (v + w)tan A : (w + u)tan B : (u + v)tan C

X(407) lies on these lines: 2,3   12,228   65,225   117,136

X(407) = crosspoint of X(4) and X(225)
X(407) = crosssum of X(I) and X(J) for these (I,J): (3,283), (21,411)


X(408) = EULER LINE INTERCEPT OF LINE X(73)X(228)

Trilinears       (v + w)cos A : (w + u)cos B : (u + v)cos C, where
                        u : v : w = X(29); e.g., u = u(A,B,C) = (sec A)/(cos B + cos C)

Barycentrics  (v + w)sin 2A : (w + u)sin 2B : (u + v)sin 2C

X(408) lies on these lines: 2,3   73,228

X(408) = crosssum of X(29) and X(412)


X(409) = EULER X(21)-1st-SUBSTITUTION POINT

Trilinears       u2 + vw : v2 + wu : w2 + uv, where
                        u : v : w = X(21); e.g., u = u(A,B,C) = 1/(cos B + cos C)

Barycentrics  a(u2 + vw) : b(v2 + wu) : c(w2 + uv)

X(409) lies on these lines: 2,3   65,1098

X(409) is the {X(21),X(29)}-harmonic conjugate of X(413). For a list of harmonic conjugates of X(409), click Tables at the top of this page.


X(410) = EULER X(29)-1st-SUBSTITUTION POINT

Trilinears       u2 + vw : v2 + wu : w2 + uv, where
                        u : v : w = X(29); e.g., u = u(A,B,C) = (sec A)/(cos B + cos C)

Barycentrics  a(u2 + vw) : b(v2 + wu) : c(w2 + uv)

X(410) lies on this line: 2,3

X(410) is the {X(21),X(29)}-harmonic conjugate of X(414). For a list of harmonic conjugates of X(410), click Tables at the top of this page.


X(411) = EULER X(21)-2nd-SUBSTITUTION POINT

Trilinears       (1/v)2 + (1/w)2 - (1/u)2 : (1/w)2 + (1/u)2 - (1/v)2 : (1/u)2 + (1/v)2 - (1/w)2, where
                        u : v : w = X(21); e.g., u = u(A,B,C) = 1/(cos B + cos C)                         = g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = cos B cos C - (cos A + cos B + cos C)cos A

Barycentrics  a[(1/v)2 + (1/w)2 - (1/u)2] : b[(1/w)2 + (1/u)2 - (1/v)2] : c[(1/u)2 + (1/v)2 - (1/w)2]

X(411) lies on these lines: 2,3   35,516   40,78   55,962   81,581   165,936   185,970   243,821   255,651

X(411) is the {X(3),X(4)}-harmonic conjugate of X(21). For a list of harmonic conjugates of X(411), click Tables at the top of this page.


X(412) = EULER X(29)-2nd-SUBSTITUTION POINT

Trilinears       (1/v)2 + (1/w)2 - (1/u)2 : (1/w)2 + (1/u)2 - (1/v)2 : (1/u)2 + (1/v)2 - (1/w)2, where
                        u : v : w = X(29); e.g., u = u(A,B,C) = (sec A)/(cos B + cos C)

Barycentrics  a[(1/v)2 + (1/w)2 - (1/u)2] : b[(1/w)2 + (1/u)2 - (1/v)2] : c[(1/u)2 + (1/v)2 - (1/w)2]

X(412) lies on these lines: 2,3   40,92   46,158   63,318   65,243   162,580   225,775   278,962

X(412) is the {X(3),X(4)}-harmonic conjugate of X(29). For a list of harmonic conjugates of X(412), click Tables at the top of this page.


X(413) = EULER X(21)-3rd-SUBSTITUTION POINT

Trilinears       u3(v2 + w2 - vw) : v3(w2 + u2 - wu) : w3(u2 + v2 - uv), where
                        u : v : w = X(21); e.g., u = u(A,B,C) = 1/(cos B + cos C)

Barycentrics  au3(v2 + w2 - vw) : bv3(w2 + u2 - wu) : cw3(u2 + v2 - uv)

X(413) lies on this line: 2,3

X(413) is the {X(21),X(29)}-harmonic conjugate of X(409). For a list of harmonic conjugates, click Tables at the top of this page.


X(414) = EULER X(29)-3rd-SUBSTITUTION POINT

Trilinears       u3(v2 + w2 - vw) : v3(w2 + u2 - wu) : w3(u2 + v2 - uv), where
                        u : v : w = X(29); e.g., u = u(A,B,C) = (sec A)1/(cos B + cos C)

Barycentrics  au3(v2 + w2 - vw) : bv3(w2 + u2 - wu) : cw3(u2 + v2 - uv)

X(414) lies on this line: 2,3

X(414) is the {X(21),X(29)}-harmonic conjugate of X(410). For a list of harmonic conjugates, click Tables at the top of this page.


X(415) = X(4)-HIRST INVERSE OF X(29)

Trilinears       (u2 - vw)sec A : (v2 - wu)sec B : (v2 - uv)sec C, where
                        u : v : w = X(21); e.g., u = u(A,B,C) = 1/(cos B + cos C)

Barycentrics  (u2 - vw)tan A : (v2 - wu)tan B : (w2 - uv)tan C

X(415) lies on these lines: 2,3   162,238

X(415) = X(4)-Hirst inverse of X(29)


X(416) = X(3)-HIRST INVERSE OF X(21)

Trilinears       (u2 - vw)cos A : (v2 - wu)cos B : (v2 - uv)cos C, where
                        u : v : w = X(29); e.g., u = u(A,B,C) = (sec A)/(cos B + cos C)

Barycentrics  (u2 - vw)sin(2A) : (v2 - wu)sin(2B) : (w2 - uv)sin(2C)

X(416) lies on this line: 2,3

X(416) = X(3)-Hirst inverse of X(21)


X(417) = X(3)-CEVA CONJUGATE OF X(185)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos A)(sec2B + sec2C)
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin 2A)(sec2B + sec2C)

X(417) lies on this line: 2,3

X(417) = X(3)-Ceva conjugate of X(185)
X(417) = crosssum of X(4) and X(1093)


X(418) = X(3)-CEVA-CONJUGATE OF X(216)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos A)(csc 2B + csc 2C)
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin 2A)(csc 2B + csc 2C)

X(418) lies on these lines: 2,3   51,216   97,110   154,160   157,161   184,577

X(418) = X(I)-Ceva conjugate of X(J) for these (I,J): (3,216), (216,217)
X(418) = crosssum of X(264) and X(317)


X(419) = X(4)-HIRST INVERSE OF X(25)

Trilinears       (u2 - vw)sec A : (v2 - wu)sec B : (v2 - uv)sec C, where
                        u : v : w = X(31); e.g., u = u(A,B,C) = a2

Barycentrics  (u2 - vw)tan A : (v2 - wu)tan B : (w2 - uv)tan C

X(419) lies on these lines: 2,3   238,242

X(419) = X(4)-Hirst inverse of X(25)


X(420) = X(4)-HIRST INVERSE OF X(427)

Trilinears       (u2 - vw)sec A : (v2 - wu)sec B : (v2 - uv)sec C, where
                        u : v : w = X(38); e.g., u = u(a,b,c) = b2 + c2

Barycentrics  (u2 - vw)tan A : (v2 - wu)tan B : (w2 - uv)tan C

X(420) lies on this line: 2,3

X(420) = X(4)-Hirst inverse of X(427)


X(421) = X(4)-HIRST INVERSE OF X(24)

Trilinears       (u2 - vw)sec A : (v2 - wu)sec B : (v2 - uv)sec C, where
                        u : v : w = X(47); e.g., u = u(A,B,C) = cos 2A

Barycentrics  (u2 - vw)tan A : (v2 - wu)tan B : (w2 - uv)tan C

X(421) lies on this line: 2,3

X(421) = X(4)-Hirst inverse of X(24)


X(422) = X(4)-HIRST INVERSE OF X(28)

Trilinears       (u2 - vw)sec A : (v2 - wu)sec B : (v2 - uv)sec C, where
                        u : v : w = X(58); e.g., u = u(a,b,c) = a/(b + c)

Barycentrics  (u2 - vw)tan A : (v2 - wu)tan B : (w2 - uv)tan C

X(422) lies on these lines: 2,3   162,242

X(422) = X(4)-Hirst inverse of X(28)


X(423) = X(4)-HIRST INVERSE OF X(27)

Trilinears       (u2 - vw)sec A : (v2 - wu)sec B : (v2 - uv)sec C, where
                        u : v : w = X(81); e.g., u = u(a,b,c) = 1/(b + c)

Barycentrics  (u2 - vw)tan A : (v2 - wu)tan B : (w2 - uv)tan C

X(423) lies on this line: 2,3

X(423) = X(4)-Hirst inverse of X(27)


X(424) = X(4)-HIRST INVERSE OF X(451)

Trilinears       (u2 - vw)sec A : (v2 - wu)sec B : (v2 - uv)sec C, where
                        u : v : w = X(191); e.g., u = u(a,b,c) = (b + c - a)(bc + ca + ab) + b3 + c3 - a3

Barycentrics  (u2 - vw)tan A : (v2 - wu)tan B : (w2 - uv)tan C

X(424) lies on this line: 2,3

X(424) = crossdifference of every pair of points on line X(647)X(1437)
X(424) = X(4)-Hirst inverse of X(451)


X(425) = X(4)-HIRST INVERSE OF X(21)

Trilinears       (u2 - vw)sec A : (v2 - wu)sec B : (v2 - uv)sec C, where
                        u : v : w = X(283); e.g., u = u(A,B,C) = (cos A)/(cos B + cos C)

Barycentrics  (u2 - vw)tan A : (v2 - wu)tan B : (w2 - uv)tan C

X(425) lies on these lines: 2,3   243,662

X(425) = X(4)-Hirst inverse of X(21)


X(426) = EULER X(19)-4th-SUBSTITUTION POINT

Trilinears       (v2 + w2)cos A : (w2 + u2)cos B : (u2 + v2)cos C, where
                        u : v : w = X(19); e.g., u = u(A,B,C) = tan A

Barycentrics  (v2 + w2)sin 2A : (w2 + u2)sin 2B : (u2 + v2)sin 2C

X(426) lies on this line: 2,3


X(427) = COMPLEMENT OF X(22)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sec A + cos(B - C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

Let LA be the line tangent to the nine-point circle at the midpoint of segment BC, and define LB and LC cyclically. The triangle formed by the lines LA, LB, LC is homothetic to the orthic triangle, and the center of homothety is X(427). (Randy Hutson, 9/23/2011)

Let (O) be the circumcircle, (N) the nine-point circle, and (IA, (IB, (IC the excircles of ABC. Let A' and A'' be the points of intersection of (O) and (IA. Let FA be the touchpoint of (N) and (IA, and let (KA) be the circle through A' and A'' that is internally tangent to (N); let LA be the touchpoint. Define FB, FC and LB, LC cyclically. The lines FALA, FBLB, FCLC concur ion X(427). (Tran Quang Hung ADGEOM #1458, August 5, 2014; see also #1459)

X(427) lies on these lines:
2,3   6,66   11,33   12,34   51,125   53,232   98,275   112,251   114,136   183,317   230,571   264,305   343,511

X(427) = midpoint of X(4) and X(378)
X(427) = isogonal conjugate of X(1176)
X(427) = isotomic conjugate of X(1799)
X(427) = inverse-in-nine-point-circle of X(468)
X(427) = inverse-in-orthocentroidal-circle of X(25)
X(427) = complement of X(22)
X(427) = complementary conjugate of X(206)
X(427) = X(112)-Ceva conjugate of X(523)
X(427) = X(39)-cross conjugate of X(141)
X(427) = crosspoint of X(4) and X(264)
X(427) = crosssum of X(I) and X(J) for these (I,J): (3,184), (6,206)
X(427) = X(4)-Hirst inverse of X(420)


X(428) = EULER X(38)-5th-SUBSTITUTION POINT

Trilinears       (v + w)sec A : (w + u)sec B : (u + v)sec C, where
                        u : v : w = X(38); e.g., u = u(a,b,c) = b2 + c2

Barycentrics  (v + w)tan A : (w + u)tan B : (u + v)tan C

X(428) lies on these lines: 2,3   132,137


X(429) = EULER X(58)-5th-SUBSTITUTION POINT

Trilinears       (v + w)sec A : (w + u)sec B : (u + v)sec C, where
                        u : v : w = X(58); e.g., u = u(a,b,c) = a/(b + c)

Barycentrics  (v + w)tan A : (w + u)tan B : (u + v)tan C

X(429) lies on these lines: 2,3   11,1104   12,37   108,961   119,136   495,1068

X(429) = isogonal conjugate of X(1798)
X(429) = X(108)-Ceva conjugate of X(523)
X(429) = crosssum of X(3) and X(1437)


X(430) = EULER X(81)-5th-SUBSTITUTION POINT

Trilinears       (v + w)sec A : (w + u)sec B : (u + v)sec C, where
                        u : v : w = X(81); e.g., u = u(a,b,c) = 1/(b + c)

Barycentrics  (v + w)tan A : (w + u)tan B : (u + v)tan C

X(430) lies on these lines: 2,3   118,136   210,594

X(430) = inverse-in-orthocentroidal-circle of X(1889)


X(431) = EULER X(283)-5th-SUBSTITUTION POINT

Trilinears       (v + w)sec A : (w + u)sec B : (u + v)sec C, where
                        u : v : w = X(283); e.g., u = u(A,B,C) = (cos A)/(cos B + cos C)

Barycentrics  (v + w)tan A : (w + u)tan B : (u + v)tan C

X(431) lies on these lines: 2,3   119,135


X(432) = EULER X(155)-6th-SUBSTITUTION POINT

Trilinears       (v2 + w2)sec A : (w2 + u2)sec B : (u2 + v2)sec C, where
                        u : v : w = X(155); e.g., u = u(A,B,C) = (cos A)(cos2B + cos2C - cos2A)

Barycentrics  (v2 + w2)tan A : (w2 + u2)tan B : (u2 + v2)tan C

X(432) lies on this line: 2,3


X(433) = EULER X(159)-6th-SUBSTITUTION POINT

Trilinears       (v2 + w2)sec A : (w2 + u2)sec B : (u2 + v2)sec C, where u : v : w = X(159)
Barycentrics  (v2 + w2)tan A : (w2 + u2)tan B : (u2 + v2)tan C

X(433) lies on this line: 2,3


X(434) = EULER X(195)-6th-SUBSTITUTION POINT

Trilinears       (v2 + w2)sec A : (w2 + u2)sec B : (u2 + v2)sec C, where u : v : w = X(195)
Barycentrics  (v2 + w2)tan A : (w2 + u2)tan B : (u2 + v2)tan C

X(434) lies on this line: 2,3


X(435) = EULER X(399)-6th-SUBSTITUTION POINT

Trilinears       (v2 + w2)sec A : (w2 + u2)sec B : (u2 + v2)sec C, where u : v : w = X(399)
Barycentrics  (v2 + w2)tan A : (w2 + u2)tan B : (u2 + v2)tan C

X(435) lies on this line: 2,3


X(436) = EULER X(48)-7th-SUBSTITUTION POINT

Trilinears       (u2 + vw)sec A : (v2 + wu)sec B : (w2 + uv)sec C, where
                        u : v : w = X(48); e.g., u(A,B,C) = sin 2A

Barycentrics  (u2 + vw)tan A : (v2 + wu)tan B : (w2 + uv)tan C

X(436) lies on these lines: 2,3   51,107   110,324   578,1093


X(437) = EULER X(214)-8th-SUBSTITUTION POINT

Trilinears       (u2 + vw)sec A : (v2 + wu)sec B : (w2 + uv)sec C, where u : v : w = X(214)
Barycentrics  (u2 + vw)tan A : (v2 + wu)tan B : (w2 + uv)tan C

X(437) lies on this line: 2,3


X(438) = EULER X(204)-9th-SUBSTITUTION POINT

Trilinears       (u2 + vw)csc A : (v2 + wu)csc B : (w2 + uv)csc C, where
                        u : v : w = X(204); e.g., u(A,B,C) = (tan A)(tan B + tan C - tan A)

Barycentrics  u2 + vw : v2 + wu : w2 + uv

X(438) lies on this line: 2,3


X(439) = EULER X(193)-10th-SUBSTITUTION POINT

Trilinears       au2 : bv2 : cw2, where
                        u : v : w = X(193); e.g., u(A,B,C) = (csc A)(cot B + cot C - cot A)

Barycentrics  (au)2 : (bv)2 : (cw)2

X(439) lies on this line: 2,3


X(440) = COMPLEMENT OF X(27)

Trilinears       bc(v + w) : ca(w + u) : ab(u + v), where
                        u : v : w = X(28); e.g., u(a,b,c) = (tan A)/(b + c)

Barycentrics  v + w : w + u : u + v

X(440) lies on these lines: 2,3   37,226   72,306   118,122   950,1104

X(440) = complement of X(27)
X(440) = X(190)-Ceva conjugate of X(525)
X(440) = crosspoint of X(2) and X(306)
X(440) = crosssum of X(I) and X(J) for these (I,J): (6,1474), (284,579)


X(441) = COMPLEMENT OF X(297)

Trilinears       bc(v + w) : ca(w + u) : ab(u + v), where
                        u : v : w = X(240); e.g., u(A,B,C) = sec A cos(A + ω)

Barycentrics  v + w : w + u : u + v

X(441) lies on these lines: 2,3   141,577   525,647

X(441) = midpoint of X(297) and X(401)
X(441) = complement of X(297)
X(441) = crosssum of X(6) and X(232)
X(441) = crossdifference of every pair of points on line X(25)X(647)


X(442)  COMPLEMENT OF SCHIFFLER POINT

Trilinears       bc(v + w) : ca(w + u) : ab(u + v), where
                        u : v : w = X(284); e.g., u(A,B,C) = (sin A)/(cos B + cos C)
Barycentrics  v + w : w + u : u + v

Let IA, IB, IC be the excenters, let AB, AC be the projections of A onto IAIB and IAIC, respectively, and define BC, BA and CA, CB cyclically. The Euler lines of the four triangles ABC, AABAC, BBCBA, CCACB concur in X(442). (Jean-Pierre Ehrmann, 11/24/01)

In the plane of triangle ABC, let DEF denote the intouch triangle of ABC, and let
HA = orthocenter of IBC
MA = midpoint of segment BC
NA = midpoint of the arc BC which does not include A
SA = reflection of I in line DE,
and define cyclically the points HB, HC, MB, MC, NB, NC, and SB, SC. The lines SAMA, SBMB, SCAMC concur in X(442), and X(442) is the pole, with respect to the incircle, of the perspectrix of the triangles HAHBHC and NANBNC. (Dominik Burek, January 18 2012)

X(442) lies on these lines: 2,3   8,495   9,46   10,12   11,214   100,943   115,120   119,125   274,325   388,956   392,946

X(442) = midpoint of X(79) and X(191)
X(442) = isogonal conjugate of X(1175)
X(442) = inverse-in-orthocentroidal-circle of X(405)
X(442) = complement of X(21)
X(442) = complementary conjugate of X(960)
X(442) = X(100)-Ceva conjugate of X(523)
X(442) = crosspoint of X(264) and X(321)
X(442) = crosssum of X(184) and X(1333)


X(443) = COMPLEMENT OF X(452)

Trilinears       bc(v + w) : ca(w + u) : ab(u + v), where
                        u : v : w = X(380)

Barycentrics  v + w : w + u : u + v

X(443) lies on these lines: 1,142   2,3   7,72   8,942   10,57   69,274   226,936   278,1038   387,940   392,962   579,966

X(443) = complement of X(452)


X(444) = EULER LINE INTERCEPT OF LINE X(19)X(232)

Trilinears       (v + w)tan A : (w + u)tan B : (u + v)tan C, where
                        u : v : w = X(256); e.g., u(a,b,c) = 1/(a2 + bc)

Barycentrics  (v + w)(sin A tan A) : (w + u)(sin B tan B) : (u + v)(sin C tan C)

X(444) lies on these lines: 2,3   19,232


X(445) = EULER X(79)-11th-SUBSTITUTION POINT

Trilinears       (v + w)csc 2A : (w + u)csc 2B : (u + v)csc 2C, where
                        u : v : w = X(79); e.g., u(a,b,c) = 1/(1 + 2 cos A)

Barycentrics  (v + w)sec A : (w + u)sec B : (u + v)sec C

X(445) lies on this line: 2,3


X(446) = CROSSPOINT OF X(98) AND X(511)

Trilinears       u(v2 + w2) : v(w2 + u2) : w(u2 + v2), where
                        u : v : w = X(98); e.g., u(A,B,C) = sec(A + ω)

Barycentrics  au(v2 + w2) : bv(w2 + u2) : cw(u2 + v2)

X(446) lies on this line: 2,3

X(446) = crosspoint of X(98) and X(511)
X(446) = crosssum of X(I) and X(J) for these (I,J): (98,511), (287,385)


X(447) = X(2)-HIRST INVERSE OF X(27)

Trilinears       bc(u2 - vw) : ca(v2 - wu) : ab(w2 - uv), where
                        u : v : w = X(28); e.g., u(a,b,c) = (tan A)/(b + c)

Barycentrics  u2 - vw : v2 - wu : w2 - uv

X(447) lies on this line: 2,3   340,540   350,811   519,648

X(447) = X(2)-Hirst inverse of X(27)


X(448) = X(2)-HIRST INVERSE OF X(21)

Trilinears       bc(u2 - vw) : ca(v2 - wu) : ab(w2 - uv), where
                        u : v : w = X(284); e.g., u(A,B,C) = (sin A)/(cos B + cos C)

Barycentrics  u2 - vw : v2 - wu : w2 - uv

X(448) lies on this line: 2,3

X(448) = X(2)-Hirst inverse of X(21)


X(449) = X(2)-HIRST INVERSE OF X(452)

Trilinears       bc(u2 - vw) : ca(v2 - wu) : ab(w2 - uv), where u : v : w = X(380)
Barycentrics  u2 - vw : v2 - wu : w2 - uv

X(449) lies on this line: 2,3

X(449) = X(2)-Hirst inverse of X(452)


X(450) = X(3)-HIRST INVERSE OF X(4)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (sec A)[cos4A - (cos B cos C)2]
                        = g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (cos A)[sec4A - (sec B sec C)2]

Barycentrics  h(A,B,C) : h(B,C,A) : h(C,A,B), where h(A,B,C) = (tan A)[cos4A - (cos B cos C)2]

X(450) lies on these lines: 2,3   107,511   155,1075   1092,1093

X(450) = isogonal conjugate of X(1942)
X(450) = crossdifference of every pair of points on line X(185)X(647)
X(450) = X(3)-Hirst inverse of X(4)


X(451) = X(4)-HIRST INVERSE OF X(424)

Trilinears       u sec A : v sec B : w sec C, where u : v : w = X(191)
Barycentrics  u tan A : v tan B : w tan C

X(451) lies on these lines: 2,3   12,108   281,1068

X(451) = X(4)-Hirst inverse of X(424)


X(452) = X(2)-HIRST INVERSE OF X(449)

Trilinears       u csc A : v csc B : w csc C, where u : v : w = X(380)
Barycentrics  u : v : w

X(452) lies on these lines: 1,329   2,3   8,9   34,347   63,938   72,145   388,1001   392,944   497,958   956,1058

X(452) = isogonal conjugate of X(2213)
X(452) = anticomplement of X(443)
X(452) = X(2)-Hirst inverse of X(449)


X(453) = POINT ALSHAIN

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C)=(cos B + cos C - cos A)2/(cos B + cos C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(453) lies on these lines: 2,3   46,1800   1014,1454


X(454) = EULER X(155)-12th-SUBSTITUTION POINT

Trilinears       u2sec A : v2sec B : w2sec C, where
                        u : v : w = X(155); e.g., u(A,B,C) = (cos A)[cos2B + cos2C - cos2A]

Barycentrics  u2tan A : v2tan B : w2tan C

X(454) lies on this line: 2,3


X(455) = EULER X(159)-13th-SUBSTITUTION POINT

Trilinears       u2sec A : v2sec B : w2sec C, where u : v : w = X(159)
Barycentrics  u2tan A : v2tan B : w2tan C

X(455) lies on this line: 2,3


X(456) = EULER X(195)-13th-SUBSTITUTION POINT

Trilinears       u2sec A : v2sec B : w2sec C, where u : v : w = X(195)
Barycentrics  u2tan A : v2tan B : w2tan C

X(456) lies on this line: 2,3


X(457) = EULER X(399)-12th-SUBSTITUTION POINT

Trilinears       u2sec A : v2sec B : w2sec C, where u : v : w = X(399)
Barycentrics  u2tan A : v2tan B : w2tan C

X(457) lies on this line: 2,3


X(458) = EULER LINE INTERCEPT OF LINE X(76)X(275)

Trilinears       u csc 2A : v csc 2B : w csc 2C, where
                        u : v : w = X(182); e.g.; u(A,B,C) = cos(A - ω)

Barycentrics  u sec A : v sec B : w sec C

X(458) lies on these lines: 2,3   6,264   76,275   141,317   239,318   273,894   315,343   340,599

X(458) = inverse-in-orthocentroidal-circle of X(297)


X(459) = X(353)-CEVA CONJUGATE OF X(4)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C)=(sec A)/(tan B + tan C - tan A)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = 1/(SA(S2 - 2SBSC))

X(459) lies on these lines:
{2,253}, {4,64}, {10,3176}, {25,3424}, {69,801}, {92,1446}, {96,3147}, {98,1301}, {196,226}, {262,3168}, {297,2996}, {458,5395}, {485,3535}, {486,3536}, {1075,3090}, {1131,1585}, {1132,1586}, {1503,3079}, {5485,5523}

X(459) = X(353)-Ceva conjugate of X(4)
X(459) = X(393)-cross conjugate of X(4)


X(460) = POINT ANTARES

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (sec A)[a2(2a2 - b2 - c2) + (b2 - c2 )2]
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(460) lies on this line: 2,3   53,1974   512,2501   685,2065

X(460) = crossdifference of every pair of points on line X(394)X(647)


X(461) = EULER LINE INTERCEPT OF LINE X(33)X(200)

Trilinears       u tan A : v tan B : w tan C, where
                        u : v : w = X(391); e.g., u(a,b,c) = bc(3a + b + c)(b + c - a)

Barycentrics  u sin A tan A : v sin B tan B : w sin C tan C

X(461) lies on these lines: 2,3   33,200


X(462) = EULER LINE INTERCEPT OF LINE X(51)X(397)

Trilinears       u tan A : v tan B : w tan C, where
                        u : v : w = X(395); e.g., u(A,B,C) = cos(B - C) + 2 cos(A + π/3)

Barycentrics  u sin A tan A : v sin B tan B : w sin C tan C

X(462) lies on these lines: 2,3   51,397   184,398  


X(463) = EULER LINE INTERCEPT OF LINE X(51)X(398)

Trilinears       u tan A : v tan B : w tan C, where
                        u : v : w = X(396); e.g., u(A,B,C) = cos(B - C) + 2 cos(A - π/3)

Barycentrics  u sin A tan A : v sin B tan B : w sin C tan C

X(463) lies on these lines: 2,3   51,398   184,397


X(464) = EULER LINE INTERCEPT OF LINE X(63)X(69)

Trilinears       u cot A : v cot B : w cot C, where u : v : w = X(387)
Barycentrics  u cos A : v cos B : w cos C

X(464) lies on these lines: 2,3   63,69

X(464) is the {X(2),X(20)}-harmonic conjugate of X(27). For a list of other harmonic conjugates of X(464), click Tables at the top of this page.


X(465) = EULER LINE INTERCEPT OF LINE X(216)X(395)

Trilinears       u cot A : v cot B : w cot C, where
                        u : v : w = X(397); e.g., u(A,B,C) = cos(B - C) - 2 cos(A + π/3)

Barycentrics  u cos A : v cos B : w cos C

X(465) lies on these lines: 2,3   216,395   396,577

X(465) is the {X(2),X(3)}-harmonic conjugate of X(466). For a list of other harmonic conjugates of X(465), click Tables at the top of this page.

X(465) = complement of X(473)


X(466) = EULER LINE INTERCEPT OF LINE X(216)X(396)

Trilinears       u cot A : v cot B : w cot C, where
                        u : v : w = X(398); e.g., u(A,B,C) = cos(B - C) - 2 cos(A - π/3)

Barycentrics  u cos A : v cos B : w cos C

X(466) lies on these lines: 2,3   216,396   395,577

X(466) is the {X(2),X(3)}-harmonic conjugate of X(465). For a list of other harmonic conjugates of X(466), click Tables at the top of this page.

X(446) = complement of X(472)


X(467) = EULER LINE INTERCEPT OF LINE X(53)X(311)

Trilinears       u csc 2A : v csc 2B : w csc 2C, where
                        u : v : w = X(52); e.g., u(A,B,C) = cos 2A cos(B - C)

Barycentrics  u sec A : v sec B : w sec C

X(467) lies on these lines: 2,3   53,311

X(467) = X(317)-Ceva conjugate of X(52)


X(468) = X(2)-LINE CONJUGATE OF X(3)

Trilinears       u csc 2A : v csc 2B : w csc 2C, where
                        u : v : w = X(187); e.g., u(a,b,c) = a(2a2 - b2 - c2)

Barycentrics  u sec A : v sec B : w sec C

X(468) lies on these lines: 2,3   98,685   107,842   111,935   230,231   250,325

X(468) = {X(1113),X(1114)}-harmonic conjugate of X(25)
X(468) = {X(1312),X(1313)}-harmonic conjugate of X(427)
X(468) = {X(2),X(1113)}-harmonic conjugate of X(1312)
X(468) = {X(2),X(1114)}-harmonic conjugate of X(1313)
For a list of other harmonic conjugates of X(468), click Tables at the top of this page.

X(468) is the midpoint between the bicentric pair P(4) and U(4).

X(468) = midpoint of X(I) and X(J) for these (I,J): (23,858), (186,403)
X(468) = isogonal conjugate of X(895)
X(468) = inverse-in-circumcircle of X(25)
X(468) = inverse-in-nine-point-circle of X(427)
X(468) = X(187)-cross conjugate of X(524)
X(468) = crossdifference of every pair of points on line X(3)X(647)
X(468) = X(2)-line conjugate of X(3)


X(469) = EULER LINE INTERCEPT OF LINE X(92)X(264)

Trilinears       u csc 2A : v csc 2B : w csc 2C, where
                        u : v : w = X(386); e.g., u(a,b,c) = a(b2 + c2 + bc + ca + ab)

Barycentrics  u sec A : v sec B : w sec C

X(469) lies on these lines: 2,3   92,264   226,273

X(469) is the {X(2),X(4)}-harmonic conjugate of X(27). For a list of other harmonic conjugates of X(469), click Tables at the top of this page.

X(469) = inverse-in-orthocentroidal-circle of X(27)


X(470) = X(15)-CROSS CONJUGATE OF X(298)

Trilinears       sin(A + π/3) csc 2A : sin(B + π/3) csc 2B : sin(C + π/3) csc 2C
Barycentrics  sin(A + π/3) sec A : sin(B + π/3) sec B : sin(C + π/3) sec 2C

X(470) lies on these lines: 2,3   18,275   264,301   298,340   302,317   343,634   394,633

X(470) = inverse-in-orthocentroidal-circle of X(471)
X(470) = X(15)-cross conjugate of X(298)
X(470) = X(4)-Hirst inverse of X(471)


X(471) = X(16)-CROSS CONJUGATE OF X(299)

Trilinears       sin(A - π/3) csc 2A : sin(B - π/3) csc 2B : sin(C - π/3) csc 2C
Barycentrics  sin(A - π/3) sec A : sin(B - π/3) sec B : sin(C - π/3) sec 2C

X(471) lies on these lines: 2,3   17,275   264,300   299,340   303,317   343,633   394,634

X(471) = inverse-in-orthocentroidal-circle of X(470)
X(471) = X(16)-cross conjugate of X(299)
X(471) = X(4)-Hirst inverse of X(470)


X(472) = X(62)-CROSS CONJUGATE OF X(303)

Trilinears       cos(A + π/3) csc 2A : cos(B + π/3) csc 2B : cos(C + π/3) csc 2C
Barycentrics  cos(A + π/3) sec A : cos(B + π/3) sec B : cos(C + π/3) sec 2C

X(472) lies on these lines: 2,3   13,275   53,395   264,298   299,317   343,621   394,622

X(472) = inverse-in-orthocentroidal-circle of X(473)
X(472) = anticomplement of X(466)
X(472) = X(62)-cross conjugate of X(303)


X(473) = X(61)-CROSS CONJUGATE OF X(302)

Trilinears       cos(A - π/3) csc 2A : cos(B - π/3) csc 2B : cos(C - π/3) csc 2C
Barycentrics  cos(A - π/3) sec A : cos(B - π/3) sec B : cos(C - π/3) sec 2C

X(473) lies on these lines: 2,3   14,275   53,396   264,299   298,317   343,622   394,621

X(473) = inverse-in-orthocentroidal-circle of X(472)
X(473) = anticomplement of X(465)
X(473) = X(61)-cross conjugate of X(302)


X(474) = EULER LINE INTERCEPT OF LINE X(10)X(56)

Trilinears       cos A - (a + b + c)/a : cos B - (a + b + c)/b : cos C - (a + b + c)/c
Trilinears       bcS - raSA : caS - rbSB : abS - rcSC)
Barycentrics  a cos A - (a + b + c) : b cos B - (a + b + c) : c cos C - (a + b + c)

X(474) lies on these lines: 2,3   8,999   10,56   35,1001   36,958   40,392   46,960   57,72   65,997   78,942   142,954   171,978   183,274   244,976   283,582   386,940   579,965   986,1054


X(475) = EULER LINE INTERCEPT OF LINE X(10)X(34)

Trilinears       sec A - (a + b + c)/a : sec B - (a + b + c)/b : sec C - (a + b + c)/c
Barycentrics  a sec A - (a + b + c) : b sec B - (a + b + c) : c sec C - (a + b + c)

X(475) lies on these lines: 2,3   8,1063   10,34   264,274   318,1068

X(475) = inverse-in-orthocentroidal-circle of X(406)


X(476) = TIXIER POINT

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/[(1 + 2 cos 2A) sin(B - C)]
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

The reflection of X(110) in the Euler line; X(476) is on the circumcircle. (Michel Tixier, 5/9/98). Also, X(476) is the center of the polar conic of X(30) with respect to the Neuberg cubic; this conic is a rectangular hyperbola passing through the incenter, the excenters, and X(30). (Peter Yff, 5/23/99)

If you have The Geometer's Sketchpad, you can view X(476).

X(476) lies on these lines: 2,842   3,477   23,94   30,74   99,850   110,523   111,230   250,933   376,841

X(476) = reflection of X(I) in X(J) for these (I,J): (146,1553), (477,3)
X(476) = isogonal conjugate of X(526)
X(476) = isotomic conjugate of X(3268)
X(476) = anticomplement of X(3258)
X(476) = cevapoint of X(30) and X(523)


X(477) = TIXIER ANTIPODE

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/[4 cos A + cos(A - 2B) + cos(A - 2C) - 3 cos(B - C)]
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

The reflection of X(476) in X(3), on the circumcircle. (Michel Tixier, 5/16/98)

X(477) lies on these lines: 3,476   30,110   50,112   74,523   107,186   376,691   378,935

X(477) = reflection of X(476) in X(3)


X(478) = CENTER OF YIU CONIC

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a[a4 - 2abc(b + c - a) - (b2 - c2)2]/(b + c - a)
Barycentrics  h(a,b,c) : h(b,c,a) : h(c,a,b), where h(a,b,c) = af(a,b,c)

Center of the Yiu conic, which passes through the points outside the circumcircle at which the excircles of ABC are tangent to the sidelines of ABC. See Paul Yiu's

The Clawson point and excircles.

X(478) lies on these lines: 6,19   9,1038   69,651   109,573   198,577   222,226


X(479) = X(269)-CROSS CONJUGATE OF X(279)

Trilinears       (tan A/2 sec A/2)2 : (tan B/2 sec B/2)2 : (tan C/2 sec C/2)2

Barycentrics  tan3(A/2) : tan3(B/2) : tan3(C/2)
                        = 1/(b + c - a)3 : 1/(c + a - b)3 : 1/(a + b - c)3

Let A' be the point in which the incircle is tangent to a circle that passes through vertices B and C, and define B' and C' cyclically. The lines AA', BB', CC' concur in X(479)

Clark Kimberling and Peter Yff, Problem 10678, American Mathematical Monthly 105 (1998) 666.

X(479) lies on these lines: 7,354   57,279   269,614

X(479) = isogonal conjugate of X(480)
X(479) = X(269)-cross conjugate of X(279)


X(480) = X(200)-CEVA CONJUGATE OF X(220)

Trilinears       (cot A/2 cos A/2)2 : (cot B/2 cos B/2)2 : (cot C/2 cos C/2)2
Barycentrics  (sin A)(cot A/2 cos A/2)2 : (sin B)(cot B/2 cos B/2)2 : (sin C)(cot C/2 cos C/2)2

The radical center of the three circles used to construct X(479). (Peter Yff, 5/6/98)

X(480) lies on these lines: 8,344   9,55   10,954   56,78   100,144

X(480) = isogonal conjugate of X(479)
X(480) = X(200)-Ceva conjugate of X(220)
X(480) = crosssum of X(269) and X(738)


X(481) = 1st EPPSTEIN POINT

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1 - 2 sec A/2 cos B/2 cos C/2
                        = 1 - 4(area)/[a(b + c - a)] : 1 - 4(area)/[b(c + a - b)] : 1 - 4(area)/[c(a + b - c)] [E. Brisse, 3/20/01]
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)
X(481) = s*X(1) - (r + 4R)*X(7)

Let S be the inner Soddy circle and SA, SB, SC the Soddy circles tangent to S. Let Ia = S∩SA, Ea = SB∩SC, and determine Ib, Ic, Eb, Ec cyclically. Then X(481) is the point of concurrence of lines IA-to-EA, IB-to-EB, IC-to-EC.

David Eppstein, "Tangent spheres and triangle centers," American Mathematical Monthly, 108 (2001) 63-66.

X(481) is the Kosnita(X(175),X(1)) point; see X(54).

X(481) lies on these lines: 1,7   174,1127   226,485

X(481) = X(79)-Ceva conjugate of X(482)


X(482) = 2nd EPPSTEIN POINT

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1 + 2 sec A/2 cos B/2 cos C/2
                        = 1 + 4(area)/[a(b + c - a)] : 1 + 4(area)/[b(c + a - b)] : 1 + 4(area)/[c(a + b - c)] [E. Brisse, 3/20/01]
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)
X(482) = s*X(1) + (r + 4R)*X(7)

Let S' be the outer Soddy circle and SA, SB, SC the Soddy circles tangent to S. Let JA = S'∩SA, EA = SB∩SC, and determine JB, JC, EB, EC cyclically. Then X(482) is the point of concurrence of lines JA-to-EA, JB-to-EB, JC-to-EC.

David Eppstein, "Tangent spheres and triangle centers," American Mathematical Monthly, 108 (2001) 63-66.

X(482) is the Kosnita(X(176),X(1)) point; see X(54).

X(482) lies on these lines: 1,7   226,486

X(482) = X(79)-Ceva conjugate of X(481)


X(483) = RADICAL CENTER OF AJIMA-MALFATTI CIRCLES

Trilinears       sec2A/4 : sec2B/4 : sec2C/4
                        = 1/(1 + cos A/2) : 1/(1 + cos B/2) : 1/(1 + cos C/2)

Barycentrics  sin A sec2A/4 : sin B sec2B/4 : sin C sec2C/4

The Ajima-Malfatti circles are described at X(179). (Peter Yff, 6/1/98)

If you have The Geometer's Sketchpad, you can view X(483).

X(483) lies on these lines: 8,178   173,180   174,175


X(484) = 1st EVANS PERSPECTOR

Trilinears       1 + 2(cos A - cos B - cos C) : 1 + 2(cos B - cos C - cos A) : 1 + 2(cos C - cos A - cos B)
Barycentrics  a[1 + 2(cos A - cos B - cos C)] : b[1 + 2(cos B - cos C - cos A)] : c[1 + 2(cos C - cos A - cos B)]

X(484) is the perspector of the excentral triangle and the triangle A'B'C', where A' is the reflection of vertex A in sideline BC and B', C' are determined cyclically. (Lawrence Evans, 10/22/98)

X(484) lies on the Neuberg cubic and these lines: 1,3   4,3483   10,191   12,79   13,1277   14,1276   30,80   63,535   74,3465   100,758   499,962   759,901   1046,1048   1138,3464   3466,3484

X(484) = midpoint of X(36) and X(3245)
X(484) = reflection of X(I) in X(J) for these (I,J): (1,36), (36,1155)
X(484) = inverse-in-circumcircle of X(35)
X(484) = inverse-in-Bevan-circle of X(1)
X(484) = isogonal conjugate of X(3065)
X(484) = X(80)-Ceva conjugate of X(1)
X(484) = crossdifference of every pair of points on line X(650)X(1100)



leftri Centers 485- 495, rightri
371, and 372: Vierkanten in een driehoek - triangle centers associated with squares.

underbar

X(485) = VECTEN POINT

Trilinears       sec(A - π/4) : sec(B - π/4) : sec(C - π/4)
                        =1/(sin A + cos A) : 1/(sin B + cos B) : 1/(sin C + cos C)
Trilinears       sin A + cos(B - C) : sin B + cos(C - A) : sin C + cos(A - B) (Peter J. C. Moses, 8/22/03)

Barycentrics  sin A sec(A - π/4) : sin B sec(B - π/4) : sin C sec(C - π/4)

Erect a square outwardly from each side of triangle ABC. Let A'B'C' be the triangle formed by the respective centers of the squares. The lines AA', BB', CC' concur in X(485). For details, visit Floor van Lamoen's site, Vierkanten in een driehoek: 1. Omgeschreven vierkanten (van Lamoen, 4/26/98) and his article "Friendship Among Triangle Centers," Forum Geometricorum, 1 (2001) 1-6. See also Paul Yiu's papers "Squares Erected on the Sides of a Triangle", and "On the Squares Erected Externally on the Sides of a Triangle".

If you have The Geometer's Sketchpad, you can view Vecten Point.

X(485) lies on these lines: 2,372   3,590   4,371   5,6   69,639   76,491   226,481   489,671

X(485) = reflection of X(488) in X(641)
X(485) = isogonal conjugate of X(371)
X(485) = isotomic conjugate of X(492)
X(485) = complement of X(488)
X(485) = anticomplement of X(641)
X(485) = X(3)-cross conjugate of X(486)
X(485) = internal center of similitude of nine-point circle and 2nd Lemoine circle


X(486) = INNER VECTEN POINT

Trilinears       sec(A + π/4) : sec(B + π/4) : sec(C + π/4)
                        =1/(sin A - cos A) : 1/(sin B - cos B) : 1/(sin C - cos C)

Trilinears       sin A - cos(B - C) : sin B - cos(C - A) : sin C - cos(A - B) (Peter J. C. Moses, 8/22/03)

Barycentrics  sin A sec(A + π/4) : sin B sec(B + π/4) : sin C sec(C + π/4)

X(486) is a perspector of triangles associated with squares that circumscribe ABC. For details and references,
see X(485). (Floor van Lamoen, 4/26/98)

If you have The Geometer's Sketchpad, you can view Inner Vecten Point.

X(486) lies on these lines: 2,371   3,615   4,372   5,6   76,492   226,482   490,671

X(486) = reflection of X(487) in X(642)
X(486) = isogonal conjugate of X(372)
X(486) = isotomic conjugate of X(491)
X(486) = complement of X(487)
X(486) = anticomplement of X(642)
X(486) = X(3)-cross conjugate of X(485)
X(486) = external center of similitude of nine-point circle and 2nd Lemoine circle


X(487) = ANTICOMPLEMENT OF X(486)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos A)(1 - csc A sin B sin C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)
Barycentrics   (b2 + c2 - a2)(a2 - 2σ) : (c2 + a2 - b2)(b2 - 2σ) : (a2 + b2 - c2)(c2 - 2σ)      (M. Iliev, 5/13/07)

X(487) is a perspector of triangles associated with squares that circumscribe ABC. (Floor van Lamoen, 4/29/98)

X(487) lies on these lines: 2,371   3,69   4,489   20,638   193,372   376,490   492,631

X(487) = reflection of X(486) in X(642)
X(487) = anticomplement of X(486)
X(487) = anticomplementary conjugate of X(638)
X(487) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,488), (489,20), (491,2)


X(488) = ANTICOMPLEMENT OF X(485)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos A)(1 + csc A sin B sin C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

Barycentrics   (b2 + c2 - a2)(a2 + 2σ) : (c2 + a2 - b2)(b2 + 2σ) : (a2 + b2 - c2)(c2 + 2σ)      (M. Iliev, 5/13/07)

X(488) is a perspector of triangles associated with squares that circumscribe ABC. For details, see Vierkanten in een driehoek: 2. Meer punten uit omgeschreven vierkanten (Floor van Lamoen, 4/29/98)

X(488) lies on these lines: 2,372   3,69   4,490   193,371   376,489   491,631

X(488) = reflection of X(485) in X(641)
X(488) = anticomplement of X(485)
X(488) = anticomplementary conjugate of X(637)
X(488) = X(I)-Ceva conjugate of X(J), for these (I,J): (4,487), (490,20), (492,2)


X(489) = CEVAPOINT OF X(20) AND X(487)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos A)(1 - csc A sin B sin C) - cos B cos C
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(489) is a perspector of triangles associated with squares that circumscribe ABC. For details and reference, see X(488). (Floor van Lamoen, 4/29/98)

X(489) lies on these lines: 3,492   4,487   20,64   30,638   176,664   376,488   485,671

X(489) = anticomplement of X(3071)
X(489) = cevapoint of X(20) and X(487)


X(490) = CEVAPOINT OF X(20) AND X(488)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos A)(1 + csc A sin B sin C) - cos B cos C
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(490) is a perspector of triangles associated with squares that circumscribe ABC. For details and reference, see X(488). (Floor van Lamoen, 4/29/98)

X(490) lies on these lines: 3,491   4,488   20,64   30,637   175,664   376,487   486,671

X(490) = anticomplement of X(3070)
X(490) = cevapoint of X(20) and X(488)


X(491) = CEVAPOINT OF X(2) AND X(487)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos A)(1 - csc A sin B sin C) + cos B cos C
Trilinears        sin(A - π/4)csc2A : sin(B - π/4)csc2B : sin(C - π/4)csc2C     (M. Iliev, 4/12/2007)
Trilinears        (1 - cot A) csc A : (1 - cot B) csc B : (1 - cot C) csc C     (M. Iliev, 4/12/2007)
Trilinears        (S - SA)/a : (S - SB)/b : (S - SC)/c     (C. Lozada, 8/07/2013)

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)
Barycentrics   b2 + c2 - a2 - 4σ : c2 + a2 - b2 - 4σ : a2 + b2 - c2 - 4σ      (M. Iliev, 5/13/07)

X(491) is a pole associated with squares that circumscribe ABC. For details and reference, see X(488). (Floor van Lamoen, 4/26/98)

X(491) lies on these lines: 2,6   3,490   4,487   5,637   76,485   315,371   372,642   488,631

X(491) = isotomic conjugate of X(486)
X(491) = anticomplement of X(615)
X(491) = X(264)-Ceva conjugate of X(492)
X(491) = cevapoint of X(2) and X(487)


X(492) = CEVAPOINT OF X(2) AND X(488)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos A)(1 + csc A sin B sin C) + cos B cos C
Trilinears        sin(A + π/4)csc2A : sin(B + π/4)csc2B : sin(C + π/4)csc2C     (M. Iliev, 4/12/2007)
Trilinears        (1 + cot A) csc A : (1 + cot B) csc B : (1 + cot C) csc C     (M. Iliev, 4/12/2007)
Trilinears        (S + SA)/a : (S + SB)/b : (S + SC)/c     (C. Lozada, 8/07/2013)

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)
Barycentrics   b2 + c2 - a2 + 4σ : c2 + a2 - b2 + 4σ : a2 + b2 - c2 + 4σ      (M. Iliev, 5/13/07)

X(492) is a pole associated with squares that circumscribe ABC. For details and reference, see X(488). (Floor van Lamoen, 4/27/98)

X(492) lies on these lines: 2,6   3,489   4,488   5,638   76,486   315,372   371,641   487,631

X(492) = isotomic conjugate of X(485)
X(492) = anticomplement of X(590)
X(492) = X(264)-Ceva conjugate of X(491)
X(492) = cevapoint of X(2) and X(488)


X(493) = 1st VAN LAMOEN HOMOTHETIC CENTER

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/(sin A + sin B sin C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(493) is a homothetic center of triangles associated with squares that circumscribe ABC. For details, see Vierkanten in een driehoek: 4. Ingeschreven vierkanten (Floor van Lamoen, 4/27/98)

X(493) is the homothetic center of triangle ABC and the Lucas homothetic triangle; see X(371). Writing t for the ratio L:W at X(371), let LA be the line through the intersections, other than A, of the A-Lucas(t) circle and sides CA and AB. Define LB and LC cyclically. Let A' = LB∩LC, and define B' and C' cyclically. Then triangle A'B'C' is homothetic to triangle ABC. If t = 1, the center of homothety is X(493); for t = -1, it is X(494); for t = 2, it is X(588); and for t = -2, it is X(589). (Randy Hutson, February 9, 2013)

X(493) lies on these lines: 25,371   39,494

X(493) = isogonal conjugate of X(3068)
X(493) = X(394)-cross conjugate of X(494)


X(494) = 2nd VAN LAMOEN HOMOTHETIC CENTER

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/(sin A - sin B sin C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(494) is a homothetic center of triangles associated with squares that circumscribe ABC. For details and reference, see X(493). (Floor van Lamoen, 4/27/98)

X(494) is the homothetic center of triangle ABC and the Lucas homothetic(-1 : 1) triangle; see X(371).

X(494) lies on these lines: 25,372   39,493

X(494) = isogonal conjugate of X(3069)
X(494) = X(394)-cross conjugate of X(493)


X(495) = JOHNSON MIDPOINT

Trilinears       2 + cos(B - C) : 2 + cos(C - A) : 2 + cos(A - B)
Barycentrics  (sin A)[2 + cos(B - C)] : (sin B)[2 + cos(C - A)] : (sin C)[2 + cos(A - B)]
X(495) = 2(R/r)*X(1) + 3X(2) - X(3)

X(495) is the midpoint of segments C1-to-P1, C2-to-P2, C3-to-P3 in the Johnson four-circle configuration.

Roger A. Johnson, Advanced Euclidean Geometry, Dover, New York, 1960, page 75.

Peter Yff, "Three concurrent congruent circles 'inscribed' in a triangle," manuscript, 1998; X(495) is the point R on page 5. (See also X(496)-X(499) and X(1478), X(1479).)

If you have The Geometer's Sketchpad, you can view Johnson-Yff Circles Internal and Johnson-Yff Circles External.

X(495) lies on these lines:
1,5   2,956   3,388   4,390   8,442   10,141   30,55   35,550   36,549   56,140   202,395   203,396   226,517   381,497   392,908   429,1068   529,993   612,1060

X(495) = complement of X(956)


X(496) = {X(1),X(5)}-HARMONIC CONJUGATE OF X(495)

Trilinears       2 - cos(B - C) : 2 - cos(C - A) : 2 - cos(A - B)
Barycentrics  (sin A)[2 - cos(B - C)] : (sin B)[2 - cos(C - A)] : (sin C)[2 - cos(A - B)]
X(496) = 2(R/r)*X(1) - 3X(2) + X(3)

Peter Yff, "Three concurrent congruent circles 'inscribed' in a triangle," manuscript, 1998; X(496) is the point R' on page 5.

X(496) lies on these lines: 1,5   2,1058   3,497   4,999   30,56   35,549   36,550   55,140   149,404   202,397   203,398   381,388   390,631   613,1069   614,1062   942,946


X(497)  CROSSPOINT OF GERGONNE POINT AND NAGEL POINT

Trilinears       1 - cos B cos C : 1 - cos C cos A : 1 - cos A cos B
Barycentrics  (sin A)(1 - cos B cos C) : (sin B)(1 - cos C cos A) : (sin C)(1 - cos A cos B)
X(497) = 2(R/r)*X(1) - 3X(2) + 2X(3)

X(497) is the harmonic conjugate of X(388) with respect to X(1) and X(4)

X(497) lies on these lines:
1,4   2,11   3,496   7,354   8,210   20,56   29,1036   30,999   35,499   36,376   57,516   65,938   69,350   80,1000   212,238   329,518   381,495   452,958   614,1040   1057,1065

X(497) = isogonal conjugate of X(1037)
X(497) = anticomplement of X(1376)
X(497) = crosspoint of X(I) and X(J) for these (I,J): (7,8), (29,314)
X(497) = crosssum of X(I) and X(J) for these (I,J): (55,56), (73,1402)
X(497) = crossdifference of every pair of points on line X(652)X(665)


X(498) = YFF CONCURRENT CONGRUENT CIRCLES POINT

Trilinears       1 + 2 sin B sin C : 1 + 2 sin C sin A : 1 + 2 sin A sin B
Barycentrics  (sin A)(1 + 2 sin B sin C) : (sin B)(1 + 2 sin C sin A) : (sin C)(1 + 2 sin A sin B)

X(498) and X(499) are harmonic conjugate points with respect to X(1) and X(2), in analogy with such pairs with respect to X(1), X(4) and with respect to X(1), X(5).

Peter Yff, "Three concurrent congruent circles 'inscribed' in a triangle," manuscript, 1998; X(498) is the point S on page 6.

X(498) lies on these lines: 1,2   3,12   4,35   5,55   9,920   36,388   37,91   46,226   47,171   56,140   141,611   191,329   255,750   345,1089


X(499) = {X(1),X(2)}-HARMONIC CONJUGATE OF X(498)

Trilinears       1 - 2 sin B sin C : 1 - 2 sin C sin A : 1 - 2 sin A sin B
Barycentrics  (sin A)(1 - 2 sin B sin C) : (sin B)(1 - 2 sin C sin A) : (sin C)(1 - 2 sin A sin B)

X(499) is the harmonic conjugate of X(498) with respect to X(1) and X(2).

Peter Yff, "Three concurrent congruent circles 'inscribed' in a triangle," manuscript, 1998; X(498) is the point S' on page 6.

X(499) lies on these lines: 1,2   3,11   4,36   5,56   12,999   17,202   18,203   35,497   46,946   47,238   55,140   57,920   80,944   141,613   255,748   348,1111   484,962


X(500) = ORTHOCENTER OF THE INCENTRAL TRIANGLE

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = a(b2 +c2 - a2 + bc)[2abc + (b + c)(a2 - (b - c)2)]

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(500) lies on these lines: 1,30   3,6   651,943

X(500) = inverse-in-Brocard-circle of X(582)
X(500) = crosspoint of X(1) and X(35)
X(500) = crosssum of X(1) and X(79)


X(501) = MIQUEL ASSOCIATE OF INCENTER

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = a[a3 - b3 - c3 - bc(a + b + c) + ab(a - b) + ac(a - c)]/(b + c)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

Miquel's theorem states that if A', B', C' are points (other than A, B, C) on sidelines BC, CA, AB, respectively, then the circles AB'C', BC'A', CA'B' meet at a point. Suppose P is a point and A' = P∩BC, B' = P∩CA, C' = P∩AB; the point in which the three circles is the Miquel associate of P. (Paul Yiu, 7/6/99)

X(501) lies on these lines: 1,229   10,662   21,214   35,110   36,58   215,1364   284,942   572,992   595,1326   759,1385

X(501) = isogonal conjugate of X(502)


X(502) = ISOGONAL CONJUGATE OF X(501)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc(b + c)/[a3 - b3 - c3 - bc(a + b + c) + ab(a - b) + ac(a - c)]
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

Let A'B'C' be the incentral triangle. Let BCA'' be the triangle similar to A'B'C' such that the segment AA'' crosses the line BC. Define B'' and C'' cyclically. The lines AA'', BB'', CC'' concur in X(502). (Randy Hutson, 9/23/2011)

X(502) lies on this line: 10,191

X(502) = isogonal conjugate of X(501)



leftri Centers 503- 510, rightri
173, 174, 258, and 351- 364 are associated with isoscelizers.

A line LA perpendicular to the internal bisector line of A is an A-isoscelizer.. Suppose X is a point not on a sideline of ABC, and let

L(A,X) = the A-isoscelizer passing through X;
E(A,X) = L(A,X)∩AC;
F(A,X) = L(A,X)∩AB;
T(A,X) = the triangle wth vertices A, E(A,X), F(A,X);
H(A,X) = A-altitude of T(A,X);
D(A,X) = distance between E(A,X) and F(A,X);
X(A) = distance between E(A,X) and F(A,X);

Cyclically define L(B,X), E(B,X), . . . , X(B) and L(C,X), E(C,X), . . . , X(C).

Each center, X(503) to X(510), is defined by Peter Yff as the point X of concurrence of isoscelers satisfying certain conditions.

Geometer's Sketchpad sketches for centers X(503)-X(510) were contributed by Peter Moses, May 7, 2005.

underbar


X(503) = 1st ISOSCELIZER POINT

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sec B/2 + sec C/2 - sec A/2
Barycentrics  af(A,B,C) : bf(B,C,A) : cf(C,A,B)

The isoscelizer equations aH(A,X) = bH(B,X) = cH(C,X) have solution X = X(503). (Peter Yff, 4/9/99)

If you have The Geometer's Sketchpad, you can view X(503).

X(503) lies on these lines: 1,167   164,361   173,844

X(503) = X(259)-Ceva conjugate of X(1)


X(504) = 2nd ISOSCELIZER POINT

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = b sin B/2 + c sin C/2 - a sin A/2
Barycentrics  af(A,B,C) : bf(B,C,A) : cf(C,A,B)

The isoscelizer equations [H(A,X)]/a = [H(B,X)]/b = [H(C,X)]/c have solution X = X(504). (Peter Yff, 4/9/99)

If you have The Geometer's Sketchpad, you can view X(504).

X(504) lies on this line: 164,173  


X(505) = 3rd ISOSCELIZER POINT

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/(sin B/2 + sin C/2 - sin A/2)
Barycentrics  af(A,B,C) : bf(B,C,A) : cf(C,A,B)

The isoscelizer equations H(A,X)D(A,X) = H(B,X)D(B,X) = H(C,X)D(C,X) have solution X = X(505). (Peter Yff, 4/9/99)

X(505) is the perspector of ABC and the excentral triangle of the excentral triangle of ABC. (Randy Hutson, 9/23/2011)

If you have The Geometer's Sketchpad, you can view X(505).

X(505) lies on this line: 40, 164

X(505) = isogonal conjugate of X(164)
X(505) = X(266)-cross conjugate of X(1)


X(506) = 4th ISOSCELIZER POINT

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos A/2)-2/3
Barycentrics  af(A,B,C) : bf(B,C,A) : cf(C,A,B)

The isoscelizer equations

X(A)[area of T(A,X)] = X(B)[area of T(B,X)] = X(C)[area of T(C,X)]

have solution X = X(506). (Peter Yff, 4/9/99)

If you have The Geometer's Sketchpad, you can view X(506).


X(507) = 5th ISOSCELIZER POINT

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (cos A/2)-1/2
Barycentrics  af(A,B,C) : bf(B,C,A) : cf(C,A,B)

The isoscelizer equations

[area of T(A,X)][X(A)]2 = [area of T(B,X)][X(B)]2 = [area of T(C,X)][X(C)]2

have solution X = X(507). (Peter Yff, 4/9/99)

If you have The Geometer's Sketchpad, you can view X(507).


X(508) = 6th ISOSCELIZER POINT

Trilinears       a-1/2sec(A/2) : b-1/2sec(B/2) : c-1/2sec(C/2)
Barycentrics  a1/2sec(A/2) : b1/2sec(B/2) : c1/2sec(C/2)

The isoscelizer equations

a[area of T(A,X)] = b[area of T(B,X)] = c[area of T(C,X)]

have solution X = X(508). (Peter Yff, 4/9/99)

If you have The Geometer's Sketchpad, you can view X(508).


X(509) = 7th ISOSCELIZER POINT

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (tan A/2)1/2
Barycentrics  af(A,B,C) : bf(B,C,A) : cf(C,A,B)

The isoscelizer equations

[area of T(A,X)]/a = [area of T(B,X)]/b = [area of T(C,X)]/c

have solution X = X(509). (Peter Yff, 4/9/99)

If you have The Geometer's Sketchpad, you can view X(509).


X(510) = 8th ISOSCELIZER POINT

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = b3/2 + c3/2 - a3/2
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

The isoscelizer equations

[area of T(A,X)]/a2 = [area of T(B,X)]/b2 = [area of T(C,X)]/c2

have solution X = X(510). (Peter Yff, 4/9/99)

If you have The Geometer's Sketchpad, you can view X(510).



leftri Centers 511- 526, rightri
30, and others, lie on the line at infinity.

Thus, a collection of collinearities reported for each of these centers comprises a family of parallel lines.
underbar

X(511) = ISOGONAL CONJUGATE OF X(98)

Trilinears       cos(A + ω) : cos(B + ω) : cos(C + ω)

                        = sin A - sin(A + 2ω) : sin B - sin(B + 2ω) : sin C - sin(C + 2ω)
                        = cos A + cos(A + 2ω) : cos B + cos(B + 2ω) : cos C + cos(C + 2ω) (cf. X(39))
                        = a(a2b2 + a2c2 - b4 - c4) : b(b2c2 + b2a2 - c4 - a4) : c(c2a2 + c2b2 - a4 - b4)     (M. Iliev, 5/13/07)

Barycentrics  sin A cos(A + ω) : sin B cos(B + ω) : sin C cos(C + ω)

X(511) = X(3) - X(6)

As the isogonal conjugate of a point on the circumcircle, X(511) lies on the line at infinity.

Let L denote the line having trilinears of X(511) as coefficients. Then L is the line passing through X(6) perpendicular to the Euler line.

X(511) is the perspector of triangle ABC and the tangential triangle of the hyperbola that passes through the points A, B, C, X(2), and X(110).

X(511) lies on these (parallel) lines:
1,256   2,51   3,6   4,69   5,141   20,185   22,184   23,110   24,1092   25,394   26,206   30,512   35,2330   36,1428   40,1045   49,2937   54,1176   55,611   56,613   66,68   67,265   74,691   83,3399   98,385   99,2698   100,2699   101,2700   102,2701   103,2702   104,2703   105,2704   106,2705   107,450   108,2707   109,2708   111,352   112,2710   114,325   125,858   140,143   154,3167   155,159   165,3097   171,181   186,249   195,2916   199,1790   230,2023   232,2211   238,3271   242,1944   283,3145   287,401   291,3510   295,3509   298,1080   299,383   343,427   355,3416   376,1992   381,599   399,2930   403,1568   468,1112   549,597   550,1353   631,3567   694,3229   843,1296   852,2972   982,1401   1113,2105   1114,2104   1194,3051   1196,1613   1292,2711   1293,2712   1294,2713   1295,2714   1297,2715   1364,1936   1370,1899   1385,1386   1437,2915   1482,3242   1757,3507   1818,2183   1976,2065   2070,3447   2095,2097   2323,3220   2653,2670   3100,3270   3124,3291

X(511) = orthopoint of X(512)
X(511) = isogonal conjugate of X(98)
X(511) = isotomic conjugate of X(290)
X(511) = anticomplementary conjugate of X(147)
X(511) = complementary conjugate of X(114)
X(511) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,114), (290,2), (297,232)
X(511) = cevapoint of X(385) and X(401)
X(511) = X(I)-cross conjugate of X(J) for these (I,J): (4,114), (290,2), (297,232)
X(511) = crosspoint of X(I) and X(J) for these (I,J): (2,290), (297,325)
X(511) = crosssum of X(I) and X(J) for these (I,J): (2,385), (6,237), (11,659), (523,868)
X(511) = crossdifference of every pair of points on line X(6)X(523)
X(511) = X(3)-Hirst inverse of X(6)
X(511) = X(I)-line conjugate of X(J) for these (I,J): (3,6), (30,523)


X(512) = ISOGONAL CONJUGATE OF X(99)

Trilinears       a(b2 - c2) : b(c2 - a2) : c(a2 - b2)
Barycentrics  a2(b2 - c2) : b2(c2 - a2) : c2(a2 - b2)

X(512) is the point in which the line of the 1st and 2nd Brocard points meets the line at infinity.

X(512) lies on these (parallel) lines: 1,875   2,3111   4,879   6,2444   25,2433   30,511   32,878   39,881   51,1640   64,2435   74,842   98,2698   99,805   100,2703   101,2702   102,2708   103,2700   104,2699   105,2711   106,2712   107,2713   108,2714   109,2701   110,249   111,843   112,2715   115,2679   187,237   263,2395   316,850   460,2501   650,2499   660,1016   670,886   764,2650   884,2440   1292,2704   1293,2705   1294,2706   1295,2707   1296,2709   1297,2710   1326,2605   1491,1734   1500,2084   1570,2451   1577,2533   1691,2483   1692,3251   1968,2909   2021,2491   2024,2507   2030,2492   2031,2510   2032,2508   2142,2143   2254,2530   2378,2379   2643,3271

X(512) = orthopoint of X(511)
X(512) = isogonal conjugate of X(99)
X(512) = isotomic conjugate of X(670)
X(512) = anticomplementary conjugate of X(148)
X(512) = complementary conjugate of X(115)
X(512) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,115), (66,125), (99,39), (110,6), (112,32), 1018,1500), (1306,1504), (1307, 1505)
X(512) = crosspoint of X(I) and X(J) for these (I,J): (4,112), (6,110), (83,99)
X(512) = crosssum of X(I) and X(J) for these (I,J): (1,1019), (2,523), (3,525), (6,669), (39,512), (100,190), (311, 850), (514,1125), (643,662)
X(512) = vertex conjugate of X(15) and X(16)
X(512) = crossdifference of every pair of points on line X(2)X(6)
X(512) = X(112)-line conjugate of X(30)


X(513) = ISOGONAL CONJUGATE OF X(100)

Trilinears       b - c : c - a : a - b
Barycentrics  ab - ac : bc - ba : ca - cb

As the isogonal conjugate of a point on the circumcircle, X(513) lies on the line at infinity.

X(513) lies on these (parallel) lines: 1,764   6,1024   7,885   9,3126   11,3025   30,511   36,238   37,876   44,649   59,651   74,2687   98,2699   99,2703   100,765   101,1308   102,2716   103,2717   104,953   105,840   106,2718   107,2719   108,2720   109,2222   110,1290   111,2721   112,2711   190,660   269,2424   320,350   484,1734   663,855   668,889   676,2488   884,3423   927,1275   957,2401   1037,1486   1052,1054   1086,3271   1292,2742   1293,2743   1294,2744   1295,2745   1296,2746   1297,2747   1361,3319   1362,3322   1364,3326   1430,2201   1835,1874   1960,3246   2473,2487   2490,2505   2500,2532   2517,2533   2529,3239   3022,3328   3123,3248

X(513) = orthopoint of X(517)
X(513) = isogonal conjugate of X(100)
X(513) = isotomic conjugate of X(668)
X(513) = anticomplementary conjugate of X(149)
X(513) = complementary conjugate of X(11)
X(513) = X(I)-Ceva conjugate of X(J) for these (I,J): (1,244), (4,11), (100,1), (101,354), (108,56), (109,65), (190,37)
X(513) = X(244)-cross conjugate of X(1)
X(513) = crosspoint of X(I) and X(J) for these (I,J): (1,100), (4,108), (58,109), (86,190)
X(513) = crosssum of X(I) and X(J) for these (I,J): (1,513), (3,521), (6,667), (10,522), (42,649), (55,650), (142,514), (442,523), (692,906), (900,1145)

X(513) = crossdifference of every pair of points on line X(1)X(6)
X(513) = X(I)-line conjugate of X(J) for these (I,J): (30,518), (36,238)


X(514) = ISOGONAL CONJUGATE OF X(101)

Trilinears       (b - c)/a : (c - a)/b : (a - b)/c
Barycentrics  b - c : c - a : a - b

X(514) is the trilinear pole of the line X(11)X(244).

As the isogonal conjugate of a point on the circumcircle, X(514) lies on the line at infinity.

X(514) lies on these (parallel) lines: 1,663   2,1022   10,764   11,3328   30,511   57,2401   74,2688   85,2140   98,2700   99,2702   100,1308   101,664   102,2723   103,2724   104,2717   105,2725   106,2726   107,2727   108,2728   109,929   110,2690   111,2729   116,1146   189,2399   190,1016   239,649   241,650   242,1459   330,3249   651,655   653,1461   659,667   661,693   1024,2402   1111,2170   1292,2736   1293,2737   1294,2738   1295,2739   1296,2740   1297,2741   1317,3322   1358,3323   1729,3188   1734,2254   1768,2958   1921,3261   2487,2516

X(514) = orthopoint of X(516)
X(514) = isogonal conjugate of X(101)
X(514) = isotomic conjugate of X(190)
X(514) = anticomplementary conjugate of X(150)
X(514) = complementary conjugate of X(116)
X(514) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,116), (7,11), (75,244), (100,142), (190,2)
X(514) = X(I)-cross conjugate of X(J) for these (I,J): (11,7), (244,75)
X(514) = crosspoint of X(2) and X(190)

X(514) = crosssum of X(I) and X(J) for these (I,J): (6,649), (37,650), (41,663), (48,652), (55,657), (213,667), (354,513), (1459,1473)

X(514) = crossdifference of every pair of points on line X(6)X(31)
X(514) = X(513)-Hirst inverse of X(812)


X(515) = ISOGONAL CONJUGATE OF X(102)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (b + c)sec A - b sec B - c sec C
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(515) is the perspector of triangle ABC and the tangential triangles of the conic that passes through the points A, B, C, X(2), and X(8).

As the isogonal conjugate of a point on the circumcircle, X(515) lies on the line at infinity.

X(515) lies on these (parallel) lines: 1,4   3,10   5,1125   8,20   9,3427   11,1319   12,2646   29,947   30,511   36,80   48,1826   55,1012   56,1210   58,3072   65,1071   71,1765   74,2689   78,3436   79,1389   98,2701   99,2708   100,2077   101,2723   102,1309   103,929   105,2730   106,2731   108,2733   109,2734   110,2695   111,2735   117,1455   119,214   145,962   153,908   165,376   200,3421   281,610   284,1065   381,551   382,1482   411,2975   484,1768   595,3073   602,1724   603,1771   631,1698   910,1146   936,2551   938,3333   956,3419   997,3452   1000,3062   1006,1746   1292,2751   1293,2757   1294,2762   1295,2765   1296,2768   1317,1537   1323,1565   1350,3416   1387,1538   1420,8086   1498,3173   1766,2321   1829,3575   1836,2099   1839,1963   1885,1902   2093,2096   2183,2250   3241,3543

X(515) = orthopoint of X(522)
X(515) = isogonal conjugate of X(102)
X(515) = anticomplementary conjugate of X(151)
X(515) = complementary conjugate of X(117)
X(515) = X(4)-Ceva conjugate of X(117)
X(515) = crossdifference of every pair of points on line X(6)X(652)


X(516) = ISOGONAL CONJUGATE OF X(103)

Trilinears       1/f(a,b,c) : 1/f(b,c,a) : 1/f(c,a,b), where f(a,b,c) : f(b,c,a) : f(c,a,b) = X(103)
                        = a2 - b2cos C - c2 cos B : b2 - c2cos A - a2 cos C : c2 - a2cos B - c2 cos A Barycentrics  a/f(a,b,c) : b/f(b,c,a) : c/f(c,a,b)

X(516) is the perspector of triangle ABC and the tangential triangles of the conic that passes through the points A, B, C, X(2), and X(7).

As the isogonal conjugate of a point on the circumcircle, X(516) lies on the line at infinity.

X(516) lies on these (parallel) lines:
1,7   2,165   3,142   4,9   8,144   11,1155   27,2328   30,511   31,1754   35,411   46,1210   55,226   57,497   63,1709   65,950   72,3059   74,2690   79,2346   80,655   98,2702   99,2700   100,908   101,2724   102,929   103,927   104,1308   105,2736   106,2737   107,2738   108,2739   109,1936   110,2688   111,2740   112,2741   118,910   146,2948   149,1768   152,1282   200,329   214,1537   238,673   255,1777   354,553   355,382   376,551   388,1697   412,1838   484,1737   550,1385   580,3073   902,3011   938,3339   944,3243   972,1543   993,1012   1058,3333   1076,1771   1086,1279   1158,3358   1284,2223   1292,2725   1293,2726   1294,2727   1295,2728   1296,2729   1317,3328   1376,3452   1389,3255   1482,1657   1490,3174   1519,2077   1538,3035   1571,2548   1572,2549   1587,1702   1588,1703   1633,3220   1698,3091   1700,2546   1701,2547   1704,2542   1705,2543   1736,2310   1829,1885   1852,1888   2017,2544   2018,2545   2321,3416   2947,3190   3021,3323   3340,3586

X(516) = orthopoint of X(514)
X(516) = isogonal conjugate of X(103)
X(516) = anticomplementary conjugate of X(152)
X(516) = complementary conjugate of X(118)
X(516) = X(4)-Ceva conjugate of X(118)
X(516) = crosssum of X(I) and X(J) for these (I,J): (3,916), (55,672)
X(516) = crossdifference of every pair of points on line X(6)X(657)


X(517) = ISOGONAL CONJUGATE OF X(104)

Trilinears       -1 + cos B + cos C : -1 + cos C + cos A : -1 + cos A + cos B
Barycentrics  (sin A)(-1 + cos B + cos C) : (sin B)(-1 + cos C + cos A) : (sin C)(-1 + cos A + cos B)
X(517) = X(1) - X(3)

As the isogonal conjugate of a point on the circumcircle, X(517) lies on the line at infinity.

X(517) lies on these (parallel) lines:
1,3   2,392   4,8   5,10   6,998   7,1000   9,374   11,1737   19,219   20,145   21,1389   30,511   33,1905   34,1753   37,573   42,1064   44,1168   52,1858   59,1870   63,956   71,1243   74,1290   78,945   88,1318   98,2703   99,2699   100,953   101,910   102,1807   103,1308   104,901   105,2742   106,2743   107,2744   108,2745   109,1455   110,1325   111,2746   112,2747   119,908   140,1125   151,1535   169,220   182,1386   201,2599   210,381   218,2082   221,3157   226,495   238,1052   244,1149   347,1439   376,2094   389,950   390,3488   399,2948   496,1210   500,2650   549,551   550,1483   572,1100   579,1108   580,595   582,602   601,1468   672,2170   840,1292   906,1951   936,1706   938,1058   958,3560   990,1350   997,1376   1006,1621   1042,1066   1046,2943   1051,2944   1068,1426   1113,2103   1114,2102   1124,2362   1148,1895   1293,2718   1294,2719   1295,2720   1296,2721   1297,2722   1817,3025   1352,3416   1361,1785   1362,3328   1364,3319   1391,1443   1411,2361   1437,3193   1451,1497   1457,1465   1478,1836   1479,1837   1490,2136   1656,1698   1702,3311   1703,3312   1788,3086   1830,1877   1838,1888   2171,2269   2182,2323   2270,2324   2329,3496   3022,3322   3061,3501   3085,3485   3125,3290   3190,3198   3197,3211   3474,3476

X(517) = orthopoint of X(513)
X(517) = isogonal conjugate of X(104)
X(517) = anticomplementary conjugate of X(153)
X(517) = complementary conjugate of X(119)
X(517) = X(4)-Ceva conjugate of X(119)
X(517) = crosspoint of X(I) and X(J) for these (I,J): (1,80), (7,88)
X(517) = crosssum of X(I) and X(J) for these (I,J): (1,36), (3,912), (44,55), (56,1455)
X(517) = crossdifference of every pair of points on line X(6)X(650)


X(518) = ISOGONAL CONJUGATE OF X(105)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = ab + ac - b2 - c2
Trilinears       as - Sω : bs - Sω : cs - Sω
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

As the isogonal conjugate of a point on the circumcircle, X(518) lies on the line at infinity.

X(518) lies on these (parallel) lines:
1,6   2,210   3,3433   7,8   10,141   11,908   20,3189   21,2346   30,511   36,42   38,42   40,1071   43,982   55,63   56,78   57,200   59,765   74,2691   80,3254   81,1390   92,1859   98,2704   99,2711   100,840   101,2725   102,2730   103,2736   104,2742   105,1280   106,2748   107,2749   108,2750   109,2751   110,2752   111,2753   112,2754   144,145   165,3158   182,1385   209,306   226,2886   239,335   241,1458   243,1897   244,899   318,1887   329,497   355,1352   474,3338   551,597   583,1009   612,940   643,2651   651,1456   668,1921   677,1814   869,2274   872,1193   896,902   910,1281   936,3333   938,2551   959,1219   961,1257   976,1468   997,999   1086   1738   1156,1320   1210,1329   1214,3190   1222,1431   1260,1617   1331,2361   1351,1482   1353,1483   1362,3323   1478,3419   1621,3219   1706,3339   1707,3052   1824,1889   1829,1843   1836,3434   1837,3436   1861,1876   1992,3241   2076,3099   2093,2097   2102,2104   2103,2105   2136,2951   2223,3286   2238,3290   2292,2667   2330,2646   2930,2948

X(518) = isogonal conjugate of X(105)
X(518) = complementary conjugate of X(120)
X(518) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,120), (335,37)
X(518) = crosspoint of X(1) and X(291)
X(518) = crosssum of X(I) and X(J) for these (I,J): (1,238), (56,1456)
X(518) = crossdifference of every pair of points on line X(6)X(513)
X(518) = X(I)-Hirst inverse of X(J) for these (I,J): (1,9), (6,1083)
X(518) = X(I)-line conjugate of X(J) for these (I,J): (1,6), (30,513)


X(519) = ISOGONAL CONJUGATE OF X(106)

Trilinears       (2a - b - c)/a : (2b - c - a)/b : (2c - a - b)/c
Barycentrics  2a - b - c : 2b - c - a : 2c - a - b

As the isogonal conjugate of a point on the circumcircle, X(519) lies on the line at infinity.

X(519) lies on these (parallel) lines: 1,2   6,996   9,1000   30,511   35,2975   36,100   37,1573   40,376   44,2325   55,956   57,3476   58,1043   63,1727   65,553   72,950   74,2692   80,908   98,2705   99,2712   101,2726   102,2731   103,2737   104,2077   105,2748   106,1120   107,2755   108,2756   109,2757   110,2758   111,2759   112,2760   121,3544   188,1128   210,392   214,1145   226,2099   238,765   244,1739   291,3227   320,668   346,1743   350,668   355,381   388,3340   405,3303   428,1829   447,648   474,3304   484,3218   495,2886   496,1329   497,3421   549,1385   573,3169   594,1100   595,2985   597,1386   599,3242   664,1323   666,1121   672,1018   751,984   958,3295   962,3543   966,3247   999,1376   1015,1575   1056,2550   1058,2551   1107,1500   1126,1220   1150,2177   1377,3297   1378,3298   1387,3036   1420,1788   1449,2345   1478,3434   1479,3436   1697,1776   1706,3333   1785,1897   1834,3454   1837,2098   1861,1870   1862,1878   2093,2094   2654,3191   3158,3524

X(519) = isogonal conjugate of X(106)
X(519) = isotomic conjugate of X(903)
X(519) = complementary conjugate of X(121)
X(519) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,121), (80,10)
X(519) = crosssum of X(I) and X(J) for these (I,J): (6,902), (56,1457)
X(519) = crossdifference of every pair of points on line X(6)X(649)
X(519) = X(I)-Hirst inverse of X(J) for these (I,J): (513, 537), (514,545)


X(520) = ISOGONAL CONJUGATE OF X(107)

Trilinears       (cos A)(sin 2B - sin 2C) : (cos B)(sin 2C - sin 2A) : (cos C)(sin 2A - sin 2B)
Barycentrics  (sin 2A)(sin 2B - sin 2C) : (sin 2B)(sin 2C - sin 2A) : (sin 2C)(sin 2A - sin 2B)

As the isogonal conjugate of a point on the circumcircle, X(520) lies on the line at infinity.

X(520) lies on these (parallel) lines: 6,2435   30,511   69,879   74,2693   98,2706   99,2713   100,2719   101,2727   102,2732   103,2738   104,2744   105,2749   106,2755   108,2761   109,2762   110,250   111,2763   112,2764   340,850   647,652   1364,2632   2451,2489

X(520) = isogonal conjugate of X(107)
X(520) = complementary conjugate of X(122)
X(520) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,122), (68,125), (110,3)
X(520) = crosspoint of X(3) and X(110)
X(520) = crosssum of X(I) and X(J) for these (I,J): (4,523), (51,647), (512,800)
X(520) = crossdifference of every pair of points on line X(4)X(6)


X(521) = ISOGONAL CONJUGATE OF X(108)

Trilinears       (sec B - sec C)(csc A) : (sec C - sec A)(csc B) : (sec A - sec B)(csc C)
Barycentrics  sec B - sec C : sec C - sec A : sec A - sec B

As the isogonal conjugate of a point on the circumcircle, X(521) lies on the line at infinity.

X(521) lies on these (parallel) lines: 6,2509   30,511   59,100   74,2694   98,2707   99,2714   101,2728   102,2733   103,2739   104,2745   109,2765   110,2766   111,2767   650,1021   651,677   656,810   1364,2968

X(521) = isogonal conjugate of X(108)
X(521) = complementary conjugate of X(123)
X(521) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,123), (100,3)
X(521) = crosspoint of X(8) and X(100)
X(521) = crosssum of X(I) and X(J) for these (I,J): (33,650), (56,513), (429,523), (663,1400)
X(521) = crossdifference of every pair of points on line X(6)X(19)


X(522) = ISOGONAL CONJUGATE OF X(109)

Trilinears       (cos B - cos C)(csc A) : (cos C - cos A)(csc B) : (cos A - cos B)(csc C)
Barycentrics  cos B - cos C : cos C - cos A : cos A - cos B

As the isogonal conjugate of a point on the circumcircle, X(522) lies on the line at infinity.

X(522) lies on these (parallel) lines: 1,1459   7,2400   9,657   11,3326   30,511   74,2695   75,3261   100,655   101,929   102,2734   103,2723   104,2716   105,2751   106,2757   107,2762   108,2765   109,1309   110,2689   111,2768   112,2769   124,2968   142,3126   190,666   240,656   243,652   649,3509   650,1639   663,1944   664,1275   693,1266   1026,2397   1027,2402   1090,2310   1292,2730   1293,2731   1294,2732   1295,2733   1296,2735   1317,3319   2490,2496   2526,3004   3063,3287

X(522) = orthopoint of X(515)
X(522) = isogonal conjugate of X(109)
X(522) = isotomic conjugate of X(664)
X(522) = complementary conjugate of X(124)
X(522) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,124), (8,11), (100,10), (190,9)
X(522) = X(11)-cross conjugate of X(8)
X(522) = crosspoint of X(I) and X(J) for these (I,J): (21,100), (75,190)
X(522) = crosssum of X(I) and X(J) for these (I,J): (6,663), (31,649), (55,652), (65,513), (603,1459), (692,1415)
X(522) = crossdifference of every pair of points on line X(6)X(41)
X(522) = X(I)-Hirst inverse of X(J) for these (I,J): (514,918), (519,528)


X(523) = ISOGONAL CONJUGATE OF X(110)

Trilinears       sin(B - C) : sin(C - A) : sin(A - B)
Barycentrics  b2 - c2 : c2 - a2 : a2 - b2

As the isogonal conjugate of a point on the circumcircle, X(523) lies on the line at infinity.

X(523) lies on these (parallel) lines: 1,2605   2,1649   4,1552   6,879   11,1090   12,2599   23,385   30,511   59,655   66,2435   74,477   75,876   98,842   99,691   100,1290   101,2690   102,2695   103,2688   104,2687   105,2752   106,2758   107,1304   108,2766   109,2689   110,476   111,2770   112,935   125,2677   140,1116   141,882   160,3164   230,231   250,648   253,2419   325,684   396,3272   656,2457   827,1287   878,3425   885,2346   930,1291   1086,2643   1101,2612   1222,2403   1292,2691   1293,2692   1294,2693   1295,2694   1296,2696   1297,2697   2525,2526   2594,2616

X(523) = orthopoint of X(30)
X(523) = isogonal conjugate of X(110)
X(523) = isotomic conjugate of X(99)
X(523) = complementary conjugate of X(125)
X(523) = anticomplementary conjugate of X(3448)

X(523) = X(I)-Ceva conjugate of X(J) for these (I,J):
(1,11), (2,115), (4,125), (99,2), (100,442), (107,4), (108,429), (110,5), (112,427), (254,136), (264,338), (476,30), (685,1503), (1113,1312), (1114,1313)

X(523) = cevapoint of X(2) and X(148)
X(523) = X(I)-cross conjugate of X(J) for these (I,J): (115,2), (125,4)
X(523) = crosspoint of X(I) and X(J) for these (I,J): (2,99), (4,107), (54,110), (112,251)
X(523) = crossdifference of every pair of points on line X(3)X(6)
X(523) = X(30)-line conjugate of X(511)
X(523) = barycentric product of X(3413) and X(3414)

X(523) = crosssum of X(I) and X(J) for these (I,J): (3,520), (5,523), (6,512), (101,692), (141,525), (184,647), (215,654), (513,942), (521,960), (924,1147)

X(523) = orthojoin of X(115)
X(523) = X(I)-Hirst inverse of X(J) for these (I,J): (6,1316), (30, 542), (512,804)


X(524) = ISOGONAL CONJUGATE OF X(111)

Trilinears       (2a2 - b2 - c2)/a : (2b2 - c2 - a2)/b : (2c2 - a2 - b2)/c
Barycentrics  2a2 - b2 - c2 : 2b2 - c2 - a2 : 2c2 - a2 - b2

As the isogonal conjugate of a point on the circumcircle, X(524) lies on the line at infinity.

X(524) lies on these (parallel) lines: 2,6   5,576   23,2930   30,511   53,317   67,858   74,2696   76,598   98,2709   99,843   100,2721   101,2729   102,2735   103,2740   104,2746   105,2753   106,2759   107,2763   108,2767   109,2768   110,2770   140,575   182,549   187,2482   237,1634   239,320   249,1691   287,1494   297,340   316,671   319,594   332,2305   338,3260   376,1350   381,1351   397,633   398,634   428,1843   441,3284   468,2192   487,1152   488,1151   551,1386   620,2030   637,3070   638,3071   694,3228   1030,1444   1084,3229   1146,1944   1238,2965   1330,1834   1901,2893   1989,2987   2094,2097   3056,3058   3241,3242

X(524) = isogonal conjugate of X(111)
X(524) = isotomic conjugate of X(671)
X(524) = complementary conjugate of X(126)
X(524) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,126), (67,141)
X(524) = X(187)-cross conjugate of X(468)
X(524) = crosssum of X(6) and X(187)
X(524) = crossdifference of every pair of points on line X(6)X(512)
X(524) = X(I)-line conjugate of X(J) for these (I,J): (4,126), (67,141)


X(525) = ISOGONAL CONJUGATE OF X(112)

Trilinears       (b cos B - c cos C)/a : (c cos C - a cos A)/b : (a cos A - b cos B)/c
Barycentrics  b cos B - c cos C : c cos C - a cos A : a cos A - b cos B

As the isogonal conjugate of a point on the circumcircle, X(525) lies on the line at infinity.

X(525) lies on these (parallel) lines: 2,1640   3,878   4,2435   30,511   74,2697   98,2710   99,249   100,2722   103,2741   104,2747   105,2754   106,2760   107,2764   109,2769   110,935   112,2867   127,1562   297,850   323,401   339,3269   441,647   669,2528   1073,2416   1636,3268   1975,2422   2474,2514   2485,2506   2513,2531   2632,2968

X(525) = isogonal conjugate of X(112)
X(525) = isotomic conjugate of X(648)
X(525) = complementary conjugate of X(127)
X(525) = X(I)-Ceva conjugate of X(J) for these (I,J): (4,127), (69,125), (76,339), (99,3), (110,141), (190,440), (253,122)

X(525) = X(I)-cross conjugate of X(J) for these (I,J): (115,68), (122,253), (125,69)
X(525) = crosspoint of X(76) and X(99)
X(525) = crosssum of X(I) and X(J) for these (I,J): (6,647), (32,512), (427,523)
X(525) = crossdifference of every pair of points on line X(6)X(25)


X(526) = ISOGONAL CONJUGATE OF X(476)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (1 + 2 cos 2A)sin(B - C)
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

As the isogonal conjugate of a point on the circumcircle, X(526) lies on the line at infinity.

X(526) lies on these (parallel) lines:
6,2492   30,511   67,879   110,351   125,3134   686,2433   895,2987   1177,2435   1769,2650   2611,3024

X(526) = isogonal conjugate of X(476)
X(526) = complementary conjugate of X(3258)
X(526) = X(110)-Ceva conjugate of X(1511)
X(526) = crosspoint of X(74) and X(110)
X(526) = crosssum of X(30) and X(523)
X(526) = crossdifference of every pair of points on line X(6)X(13)



leftri Centers 527- 565 rightri
were added to ETC on 1/1/01.

underbar

X(527) = DIRECTION OF VECTOR AX + BX + CX, where X = X(7)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(a,b,c) = 1/[a(b + c - a)], y = x(b,c,a), z = x(c,a,b)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(527) lies on the line at infinity.

X(527) lies on these (parallel) lines: 2,7   30,511   44,1086   69,2321   72,1242   190,320   200,3474   239,1266   269,2324   347,1419   376,2096   381,2095   390,3241   551,993   599,2097   651,2323   666,673   896,3011   1156,3254   1478,2093   1738,1757   2340,3000   2346,3255   2551,3339   2951,3174

X(527) = isogonal conjugate of X(2291)
X(527) = isotomic conjugate of X(1121)
X(527) = crosssum of X(6) and X(1055)
X(527) = crossdifference of every pair of points on line X(6)X(663)


X(528) = DIRECTION OF VECTOR AX + BX + CX, where X = X(11)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(A,B,C) = 1 - cos(B-C), y = x(B,C,A), z = x(C,A,B)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(528) lies on the line at infinity.

X(528) lies on these (parallel) lines: 1,1086   2,11   7,664   8,190   9,80   30,511   104,376   119,381   142,214   153,3543   377,3303   428,1824   549,1484   962,3189   1279,1738   1329,1479   1537,3174   1699,3158   1750,2900   1770,3555   2094,3474   3008,3246   3032,3034

X(528) = isogonal conjugate of X(840)
X(528) = crossdifference of every pair of points on line X(6)X(665)
X(528) = X(519)-Hirst inverse of X(522)


X(529) = DIRECTION OF VECTOR AX + BX + CX, where X = X(12)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(A,B,C) = 1 + cos(B-C), y = x(B,C,A), z = x(C,A,B)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(529) lies on the line at infinity.

X(529) lies on these (parallel) lines: 2,12   8,3474   30,511   36,3035   46,1706   329,3476   428,1828   484,1145   495,993   908,1319   956,1478   1001,1056   1146,3509   1376,3421   2098,3058   2478,3304   3036,3218


X(530) = DIRECTION OF VECTOR AX + BX + CX, where X = X(13)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(A,B,C) = csc(A + π/3), y = x(B,C,A), z = x(C,A,B)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(530) lies on the line at infinity.

X(530) lies on these (parallel) lines: 2,13   14,671   30,511   99,299   115,395   148,3181   187,396   298,316   619,2482

X(530) = isogonal conjugate of X(2378)


X(531) = DIRECTION OF VECTOR AX + BX + CX, where X = X(14)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(A,B,C) = csc(A - π/3), y = x(B,C,A), z = x(C,A,B)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(531) lies on the line at infinity.

X(531) lies on these (parallel) lines: 2,14   13,671   30,511   99,298   115,396   148,3180   187,395   299,316   618,2482

X(531) = isogonal conjugate of X(2379)


X(532) = DIRECTION OF VECTOR AX + BX + CX, where X = X(17)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(A,B,C) = csc(A + π/6), y = x(B,C,A), z = x(C,A,B)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(532) lies on the line at infinity.

X(532) lies on these (parallel) lines: 2,17   13,298   14,622   15,616   16,299   30,511   395,624   396,618   397,635

X(532) = isogonal conjugate of X(2380)


X(533) = DIRECTION OF VECTOR AX + BX + CX, where X = X(18)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(A,B,C) = csc(A - π/6), y = x(B,C,A), z = x(C,A,B)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(533) lies on the line at infinity.

X(533) lies on these (parallel) lines: 2,18    13,621   14,299   15,298  16,617    30,511   395,619   396,623   398,636

X(533) = isogonal conjugate of X(2381)


X(534) = DIRECTION OF VECTOR AX + BX + CX, where X = X(19)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(A,B,C) = tan A, y = x(B,C,A), z = x(C,A,B)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(534) lies on the line at infinity.

X(534) lies on these (parallel) lines: 2,19   30,511   553,1407   1441,1839


X(535) = DIRECTION OF VECTOR AX + BX + CX, where X = X(36)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(A,B,C) = 1 - 2 cos A, y = x(B,C,A), z = x(C,A,B)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(535) lies on the line at infinity.

X(535) lies on these (parallel) lines: 2,36   8,3245   10,1155   30,511   63,484   80,3218   214,908   226,551   376,2077   388,2078   428,1878   903,1168


X(536) = DIRECTION OF VECTOR AX + BX + CX, where X = X(37)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(a,b,c) = b + c, y = x(b,c,a), z = x(c,a,b)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(536) lies on the line at infinity.

X(536) lies on these (parallel) lines: 2,37   30,511   42,2230   44,190   141,2321   335,903   889,3227   894,1100   1086,1266   2228,3123   2234,3009   2325,3008

X(536) = isogonal conjugate of X(739)
X(536) = isotomic conjugate of X(3227)
X(536) = crossdifference of every pair of points on line X(6)X(667)


X(537) = DIRECTION OF VECTOR AX + BX + CX, where X = X(38)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(a,b,c) = b2 + c2, y = x(b,c,a), z = x(c,a,b)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(537) lies on the line at infinity.

X(537) lies on these (parallel) lines: 1,190   2,38   10,1086   30,511   37,551   75,668   192,3241

X(537) = isogonal conjugate of X(2382)
X(537) = X(513)-Hirst inverse of X(519)


X(538) = DIRECTION OF VECTOR AX + BX + CX, where X = X(39)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(a,b,c) = a(b2 + c2), y = x(b,c,a), z = x(c,a,b)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(538) lies on the line at infinity.

X(538) lies on these (parallel) lines: 2,39   30,511   32,1003   69,2549   75,1573   99,187   115,325   148,316   183,574   230,620   262,3545   350,1015   381,3095   591,3102   599,3094   671,1916   886,3228   1316,3292   1500,1909   1569,2021   1991,3103

X(538) = isogonal conjugate of X(729)
X(538) = isotomic conjugate of X(3228)
X(538) = crossdifference of every pair of points on line X(6)X(669)


X(539) = DIRECTION OF VECTOR AX + BX + CX, where X = X(54)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(A,B,C) = 1/cos(B-C), y = x(B,C,A), z = x(C,A,B)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(539) lies on the line at infinity.

X(539) lies on these (parallel) lines: 2,54   3,3519   5,1493   30,511   113,2914   155,195   265,1568   2072,3292

X(539) = isogonal conjugate of X(2383)


X(540) = DIRECTION OF VECTOR AX + BX + CX, where X = X(58)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(a,b,c) = a/(b + c), y = x(b,c,a), z = x(c,a,b)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(540) lies on the line at infinity.

X(540) lies on these (parallel) lines: 2,58   30,511   340,447   376,3430


X(541) = DIRECTION OF VECTOR AX + BX + CX, where X = X(74)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(A,B,C) = 1/(cos A - 2 cos B cos C), y = x(B,C,A), z = x(C,A,B)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(541) lies on the line at infinity.

X(541) lies on these (parallel) lines: 2,74   30,511   110,376   125,381   265,3426   394,399   3028,3058   3448,3543

X(541) = isogonal conjugate of X(841)


X(542) = DIRECTION OF VECTOR AX + BX + CX, where X = X(98)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(A,B,C) = sec(A + ω), y = x(B,C,A), z = x(C,A,B)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(542) lies on the line at infinity.

X(542) lies on these (parallel) lines: 2,98   3,67   4,576   5,575   6,13   30,511   68,1177   69,74   141,549   146,148   159,2931   161,1619   230,2030   428,1112   858,3292   1350,3534   1365,2606   1550,1551   1569,3094   1648,2502   1843,1986   1853,3167   3023,3028   3024,3027   3043,3044

X(542) = orthopoint of X(690)
X(542) = isogonal conjugate of X(842)
X(542) = crossdifference of every pair of points on line X(6)X(526)
X(542) = X(30)-Hirst inverse of X(523)


X(543) = DIRECTION OF VECTOR AX + BX + CX, where X = X(99)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(a,b,c) = bc/(b2 - c2), y = x(b,c,a), z = x(c,a,b)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(543) lies on the line at infinity.

X(543) lies on these (parallel) lines: 2,99   22,3455   25,2936   30,511   98,376   114,381   147,3543   549,1153   598,1569   626,1975   1641,2502   2421,3016   3023,3058   3027,3325   3044,3048

X(543) = isogonal conjugate of X(843)
X(543) = crossdifference of every pair of points on line X(6)X(351)


X(544) = DIRECTION OF VECTOR AX + BX + CX, where X = X(101)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(a,b,c) = a/(b - c), y = x(b,c,a), z = x(c,a,b)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(544) lies on the line at infinity.

X(544) lies on these (parallel) lines: 2,101   30,511   63,1018   103,376   118,381   152,3543   3022,3058


X(545) = DIRECTION OF VECTOR AX + BX + CX, where X = X(190)

Trilinears       f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = (2ax - by - cz)/a, x = x(a,b,c) = bc/(b - c), y = x(b,c,a), z = x(c,a,b)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(545) lies on the line at infinity.

X(545) lies on these (parallel) lines: 2,45   30,511   44,1266   63,2161   321,1227

X(545) = isogonal conjugate of X(2384)
X(545) = X(514)-Hirst inverse of X(519)


X(546) = MIDPOINT OF X(4) AND X(5)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 3 cos(B - C) - 2 cos A,
                     = cos A + 6 cos B cos C : cos B + 6 cos C cos A : cos C + 6 cos A cos B

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(546) = X(5)-of-Euler-triangle

Let MA denote the point in which the A-median meets side BC. On 11/05/03, Andrew Crane noted that X(546) is the radical center of circles (A), (B), (C), where (A) denotes the circle centered at A and passing through MA, and (B) and (C) are defined cyclically.

X(546) lies on these lines: 2,3   13,398   14,397   113,137   156,578   946,952

X(546) = midpoint of X(I) and X(J) for these (I,J): (4,5), (382,550)
X(546) = reflection of X(I) in X(J) for these (I,J): (140,5), (548,140)
X(546) = inverse-in-orthocentroidal-circle of X(382)
X(546) = complement of X(550)
X(546) = anticomplement of X(3530)


X(547) = MIDPOINT OF X(2) AND X(5)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 5 cos(B - C) + 2 cos A,
                     = 7 cos A + 10 cos B cos C : 7 cos B + 10 cos C cos A : 7 cos C + 10 cos A cos B

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(547) lies on the Euler line. (Antreas Hatzipolakis, 1/20/00, Hyacinthos #201)

X(547) lies on these lines: 2,3   551,952

X(547) = midpoint of X(I) and X(J) for these (I,J): (2,5), (381,549)
X(547) = reflection of X(140) in X(2)
X(547) = complement of X(549)


X(548) = MIDPOINT OF X(5) AND X(20)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = - cos(B - C) + 6 cos A,
                     = 5 cos A - 2 cos B cos C : 5 cos B - 2 cos C cos A : 5 cos C - 2 cos A cos B
                     = 2 sec A - 5 sec B sec C : 2 sec B - 5 sec C sec A : 2 sec C - 5 sec A sec B

Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(548) lies on the Euler line. (Antreas Hatzipolakis, 1/20/00, Hyacinthos #201)

X(548) = midpoint of X(I) and X(J) for these (I,J): (3,550), (5,20)
X(548) = reflection of X(I) in X(J) for these (I,J): (140,3), (546,140)


X(549) = MIDPOINT OF X(2) AND X(3)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = cos(B - C) + 4 cos A,
                     = 5 cos A + 2 cos B cos C : 5 cos B + 2 cos C cos A : 5 cos C + 2 cos A cos B
                     = 3 cos A + 2 sin B sin C : 3 cos B + 2 sin C sin A : 3 cos C + 2 sin A sin B
                     = 2 sec A + 5 sec B sec C : 2 sec B + 5 sec C sec A : 2 sec C + 5 sec A sec B
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(549) lies on the Euler line. (Antreas Hatzipolakis, 1/20/00, Hyacinthos #201)

X(549) lies on these lines: 2,3   15,395   16,396   35,496   36,495   141,542   182,524   230,574   302,617   303,616   511,597   517,551

X(549) = midpoint of X(I) and X(J) for these (I,J): (2,140), (5,2), (381,547)
X(549) = reflection of X(I) in X(J) for these (I,J): (14,619), (148,13), (616,99), (622,299)
X(549) = complement of X(381)
X(549) = anticomplement of X(547)


X(550) = MIDPOINT OF X(3) AND X(20)

Trilinears       f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = - cos(B - C) + 4 cos A,
                     = 3 cos A - 2 cos B cos C : 3 cos B - 2 cos C cos A : 3 cos C - 2 cos A cos B
                     = 2 sec A - 3 sec B sec C : 2 sec B - 3 sec C sec A : 2 sec C - 3 sec A sec B
Barycentrics  (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(550) lies on the Euler line. (Antreas Hatzipolakis, 1/20/00, Hyacinthos #201)

X(550) lies on these lines: 2,3   15,397   16,398   35,495   36,496   40,952   74,930   156,1092   165,355

X(550) = midpoint of X(3) and X(20)
X(550) = reflection of X(I) in X(J) for these (I,J): (3,548), (4,140), (5,3), (382,546)
X(550) = complement of X(382)
X(550) = anticomplement of X(546)


X(551) = MIDPOINT OF X(1) AND X(2)

Trilinears       (4a + b + c)/a : (4b + c + a)/b : (4c + a + b)/c
Barycentrics  4a + b + c : 4b + c + a : 4c + a + b

X(551) lies on these lines: 1,2   30,946   37,537   56,553   86,99   142,214   226,535   354,392   376,516   381,515   514,676   517,549   518,597   527,993   547,952

(Antreas Hatzipolakis, 1/24/00, Hyacinthos #223)

X(551) = midpoint of X(I) and X(J) for these (I,J): (2,1125), (10,2)
X(551) = reflection of X(I) in X(J) for these (I,J): (14,619), (148,13), (616,99), (622,299)


X(552) = POINT MAIA I

Trilinears       1/[a(b + c - a)(b + c)2] : 1/[b(c +a - b)(c + a)2] : 1/[c(a + b - c)(a + b)2]
Barycentrics  1/[(b + c - a)(b + c)2] : 1/[(c + a - b)(c + a)2] : 1/[(a + b - c)(a + b)2]

X(552) lies on this line: 261,873

X(552) = X(757)-cross conjugate of X(1509)


X(553) = POINT MAIA II

Trilinears       bc(2a + b + c)/(b + c - a) : ca(2b + c + a)/(c + a - b) : ab(2c + a + b)/(a + b - c)
Barycentrics  (2a + b + c)/(b + c - a) : (2b + c + a)/(c + a - b) : (2c + a + b)/(a + b - c)

X(553) lies on these lines: 1,376   2,7   30,942   56,551   65,519   354,516

X(553) = crosssum of X(55) and X(1334)


X(554) = INTERSECTION OF LINES X(1)X(30) AND X(14)X(226)

Trilinears       sec(A/2) csc(A/2 + π/3) : sec(B/2) csc(B/2 + π/3) : sec(C/2) csc(C/2 + π/3)
Barycentrics  sin A sec(A/2) csc(A/2 + π/3) : sin B sec(B/2) csc(B/2 + π/3) : sin C sec(C/2) csc(C/2 + π/3)

Suppose X and Y are triangle centers. Let

YA = (Y of the triangle XBC),
YB = (Y of the triangle XCA),
YC = (Y of the triangle XAB).

Let A' = (XYA intersect BC), and define B' and C' cyclically. In

Clark Kimberling, "Major Centers of Triangles," Amer. Math. Monthly 104 (1997) 431-438,

Question A is this: for what choices of X and Y do the lines AA', BB', CC' concur? A solution (X,Y) will here be called the (X,Y)-answer to Question A. X(554) is the (X(1),X(13))-answer to Question A. (In the reference, see (9) on page 435, with Y = X(13).)

X(554) lies on these lines: 1,30   7,1082   14,226   75,299


X(555) = (X(1),X(7))-ANSWER TO QUESTION A

Trilinears       sec3(A/2) : sec3(B/2) : sec3(C/2)
Barycentrics  sin A sec3(A/2) : sin B sec3(B/2) : sin C sec3(C/2)

X(555) lies on these lines: 7,177   234,1088

X(555) = X(234)-cross conjugate of X(7)


X(556) = (X(1),X(8))-ANSWER TO QUESTION A

Trilinears       csc A csc A/2 : csc B csc B/2 : csc C csc C/2
Barycentrics  csc A/2 : csc B/2 : csc C/2

X(556) lies on these lines: 8,177   75,234   312,2090

X(556) = isotomic conjugate of X(174)


X(557) = (X(1),X(9))-ANSWER TO QUESTION A

Trilinears       sec A/2 cot A/4 : sec B/2 cot B/4 : sec C/2 cot C/4
Barycentrics   cos2A/4 : cos2B/4 : cos2C/4

X(557) lies on these lines: 2,178   1274,1488


X(558) = (X(1),X(57))-ANSWER TO QUESTION A

Trilinears       sec A/2 tan A/4 : sec B/2 tan B/4 : sec C/2 tan C/4
Barycentrics  sin2(A/4) : sin2(B/4) : sin2(C/4)

X(558) lies on this line: 2,178


X(559) = (X(1),X(15))-ANSWER TO QUESTION A

Trilinears       (sec A/2) sin(A/2 + π/3) : (sec B/2) sin(B/2 + π/3) : (sec C/2) sin(C/2 + π/3)
Barycentrics  (sin A/2) sin(A/2 + π/3) : (sin B/2) sin(B/2 + π/3) : (sin C/2) sin(C/2 + π/3)

X(559) lies on these lines: 1,3   14,226   299,319


X(560)  4th POWER POINT

Trilinears       a4 : b4 : c4
Trilinears       a2(SA - Sω) : b2(SB - Sω) : c2(SC - Sω)
Barycentrics  a5 : b5 : c5

X(560) lies on these lines: 1,82   31,48   41,872   42,584   100,697   101,713   110,715   717,825   719,827

X(560) = isogonal conjugate of X(561)
X(560) = isotomic conjugate of X(1928)
X(560) = crosssum of X(75) and X(304)


X(561)  ISOGONAL CONJUGATE OF 4th POWER POINT

Trilinears       a - 4 : b - 4 : c - 4
Barycentrics  a -3 : b -3 : c -3

X(561) lies on these lines: 1,718   2,716   6,720   31,722   32,724   38,75   63,799   76,321   92,304   313,696

X(561) = isogonal conjugate of X(560)
X(561) = isotomic conjugate of X(31)
X(561) = cevapoint of X(75) and X(304)
X(561) = X(313)-cross conjugate of X(76)


X(562) = TRILINEAR QUOTIENT X(2)*X(50)/X(49)

Trilinears       csc A tan 3A : csc B tan 3B : csc C tan 3C
Barycentrics  tan 3A : tan 3B : tan 3C

X(562) lies on this line: 4,93

Clark Kimberling and Cyril Parry, "Products, Square Roots, and Layers in Triangle Geometry," Mathematics and Informatics Quarterly 10 (2000) 9-22; on page 21, section 8.


X(563) = TRILINEAR PRODUCT X(47)*X(48)

Trilinears        sin 4A : sin 4B : sin 4C
                        = tan 2B + tan 2C : tan 2C + tan 2A : tan 2A + tan 2B
Barycentrics  sin A sin 4A : sin B sin 4B : sin C sin 4C

X(563) lies on these lines: 19,163   48,255

Clark Kimberling and Cyril Parry, "Products, Square Roots, and Layers in Triangle Geometry," Mathematics and Informatics Quarterly 10 (2000) 9-22; on page 21, section 8.


X(564) = INTERSECTION OF LINES X(1)X(1048) AND X(47,91)

Trilinears        cos(2B - 2C) : cos(2C - 2A) : cos(2A - 2B)
Barycentrics  sin A cos(2B - 2C) : sin B cos(2C - 2A) : sin C cos(2A - 2B)

X(564) lies on these lines: 1,1048   47,91

Clark Kimberling and Cyril Parry, "Products, Square Roots, and Layers in Triangle Geometry," Mathematics and Informatics Quarterly 10 (2000) 9-22; on page 21, section 8.


X(565) = INTERSECTION OF LINES X(49)X(93) AND X(143,324)

Trilinears        cos(3B - 3C) : cos(3C - 3A) : cos(3A - 3B)
Barycentrics  sin A cos(3B - 3C) : sin B cos(3C - 3A) : sin C cos(3A - 3B)

X(565) lies on these lines: 49,93   143,324

Clark Kimberling and Cyril Parry, "Products, Square Roots, and Layers in Triangle Geometry," Mathematics and Informatics Quarterly 10 (2000) 9-22; on page 21, section 8.



leftri Centers 566 - 584 rightri
are on the Brocard axis, L(3,6). Each is the center X of a circle
meeting the sides of triangle ABC with three equal angles at X.
Let AB, AC, BC, BA, CA, CB denote the meeting-points; e.g., AB and CB
are on side CA. The equal angles are given by

D = angle(ABXAC) = angle(BCXBA) = angle(CAXCB)

Then trilinears for X are given by

X = sin A + cot D/2 cos A : sin B + cot D/2 cos B : sin C + cot D/2 cos C.

Definitions: Y is the orthogonal of X if D(X) + D(Y) = π/2;
Y is the harmonic of X if X and Y are harmonic conjugates with respect to X(3) and X(6);
Y is the orthoharmonic if Y is the harmonic of the orthogonal of X. The centers in this section were contributed by Edward Brisse, December, 2000.

underbar


X(566) = HARMONIC OF X(50)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin A + cos A cot D/2, where cot D/2 = 4*area/(a2 + b2 + c2 - 6R2), where R = abc/(4*area)
Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where fa,b,c) = a[16(b2 + c22 - 3a2b2c2]      (M.Iliev, 5/13/07)

Barycentrics  af(a,b,c) : bf(b,c,a) cf(c,a,b)

X(566) lies on these lines: 2,94   3,6   53,1594   233,1879   2165,2963

X(566) = inverse-in-Brocard-circle of X(50)
X(566) = crosssum of X(6) and X(381)


X(567) = ORTHOGONAL OF X(50)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin A + cos A cot D/2, where where cot D/2 = (a2 + b2 + c2 - 6R2)/(4*area), where R = abc/(4*area)
Barycentrics  af(a,b,c) : bf(b,c,a) cf(c,a,b)

X(567) lies on these lines: 3,6   5,49   51,2070   140,3580   156,309   184,381   546,1614   1092,3526   1147,1656   1154,1994   1658, 3567   1986,3520

X(567) = inverse-in-Brocard-circle of X(568)


X(568) = ORTHOHARMONIC OF X(50)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin A + cos A cot D/2, where where cot D/2 = (6R2 - a2 - b2 - c2)/(4*area), where R = abc/(4*area)
Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a[3*R2(b2 + c2 - a2) + a2b2 + a2c2 - b4 - c4], where R = abc/(4*area)     (Wimalasiri Perera, August 29, 2011)

Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(568) lies on these lines: 2,1154   3,6   4,94   5,3567   24,49   30,3060   51,381   54,1658   68,973   156,3518   184,2070   185,382   186,1994   195,1147   373,1656   549,2979   1216,3526

X(568) = reflection of X(381) in X(51)
X(568) = inverse-in-Brocard-circle of X(567)


X(569) = HARMONIC OF X(52)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin A + cot D/2 cos A,
                        cot D/2 = (2e3 + e2 - e1)/[64*(area)3], where
                        e1 = a6 + b6 + c6
                        e2 = a4(b2 + c2) + b4(c2 + a2) + c4(a2 + b2)
                        e3 = a2b2c2

Barycentrics  (sin A)f(A,B,C): (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(569) lies on these lines: 2,54   3,6   5,156   26,51   140,343

X(569) = inverse-in-Brocard-circle of X(52)


X(570) = ORTHOGONAL OF X(52)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin A + sin 2A cos(B - C)     (Joe Goggins, 11/26/08)
Trilinears        g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin A + cot D/2 cos A,
                        cot D/2 = [64*(area)3]/(2e3 + e2 - e1), where
                        e1, e2, e3 are as for X(569)

Barycentrics  (sin A)f(A,B,C): (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(570) lies on these lines: 2,311   3,6   53,232   115,128   140,231   157,184

X(570) = inverse-in-Brocard-circle of X(571)
X(570) = complement of X(311)
X(570) = crosspoint of X(2) and X(54)
X(570) = crosssum of X(5) and X(6)


X(571) = ORTHOHARMONIC OF X(52)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin A cos 2A     (M. Iliev, 4/12/07)
Barycentrics  (sin A)f(A,B,C): (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(571) lies on these lines: 3,6   4,96   66,248   112,393   160,184   206,237   230,427   608,913

X(571) = isogonal conjugate of X(5392)
X(571) = inverse-in-Brocard-circle of X(570)
X(571) = X(4)-Ceva conjugate of X(184)
X(571) = crosspoint of X(2) and X(70)
X(571) = crosssum of X(I) and X(J) for these (I,J): (6,26), (338,525)
X(571) = barycentric product of X(371) and X(372)


X(572) = ORTHOGONAL OF X(58)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = cos(A - U), where cot U = cot(A/2) cot(B/2) cot(C/2)     (Joe Goggins, 11/26/08)
Trilinears        g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin A + cot D/2 cos A,
                        cot D/2 = (a + b + c)2/(4*area)

Barycentrics  (sin A)f(A,B,C): (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(572) = s*X(3) + r*cot(ω)*X(6)

X(572) lies on these lines: 1,604   3,6   9,48   51,199   54,71   103,825   165,1051   169,610   184,1011   219,947   261,662   517,1100   594,952   631,966

X(572) = inverse-in-Brocard-circle of X(573)
X(572) = crosssum of X(11) and X(661)


X(573) = ORTHOHARMONIC OF X(58)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = cos(A + U), where cot U = cot(A/2) cot(B/2) cot(C/2)     (Joe Goggins, 11/26/08)
Trilinears        g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin A + cot D/2 cos A,
                        cot D/2 = - (a + b + c)2/(4*area)

Trilinears        h(a,b,c) : h(b,c,a) : h(c,a,b), where h(a,b,c) = s cos A - r sin A, s = semiperimeter, r = inradius

Barycentrics  (sin A)f(A,B,C): (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(573) = s*X(3) - r*cot(ω)*X(6)

X(573) is the internal center of similitude of the circumcircle and Apollonius circle. The external center is X(386). (Peter J. C. Moses, 8/22/03)

X(573) lies on these lines: 1,941   3,6   4,9   20,391   36,604   37,517   43,165   51,1011   55,181   101,102   109,478   184,199   256,981   346,1018   347,1020

X(573) = reflection of X(991) in X(3)
X(573) = inverse-in-Brocard-circle of X(572)
X(573) = X(333)-Ceva conjugate of X(1)
X(573) = crosspoint of X(59) and X(190)
X(573) = crosssum of X(11) and X(649)
X(573) = crossdifference of every pair of points on line X(523)X(1459)


X(574) = HARMONIC OF X(187)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin A + cot D/2 cos A,
                        cot D/2 = 12*area/(a2 + b2 + c2)

Trilinears        g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = a(a2 - 2b2 - 2c2)

Trilinears        sin A + 3 cos A tan ω : sin B + 3 cos B tan ω : sin C + 3 cos C tan ω (Peter J. C. Moses, 8/22/03)

Barycentrics  (sin A)f(A,B,C): (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(574) lies on these lines: 2,99   3,6   55,1015   110,353   183,538   230,549   232,378   805,843

X(574) = isogonal conjugate of X(598)
X(574) = inverse-in-Brocard-circle of X(187)
X(574) = internal center of similitude of circumcircle and Moses circle
X(574) = crossdifference of every pair of points on line X(351)X(523)


X(575) = ORTHOGONAL OF X(187)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin A + cot D/2 cos A,
                        cot D/2 = (a2 + b2 + c2)/(12*area)

Trilinears        g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = 3 sin A + cos A cot ω   (Peter J. C. Moses, 7/20/03)

Trilinears        h(A,B,C) : h(B,C,A) : h(C,A,B), where h(A,B,C) = cos A + 3 sin A tan ω   (Peter J. C. Moses, 8/22/03)

Barycentrics  (sin A)f(A,B,C): (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(575) = X(3) + 3X(6)

X(575) lies on these lines: 3,6   4,598   5,542   23,51   54,895   110,373   140,524   141,629

X(575) = midpoint of X(I) and X(J) for these (I,J): (3,576), (6,182)
X(575) = inverse-in-Brocard-circle of X(576)


X(576) = ORTHOHARMONIC OF X(187)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin A + cot D/2 cos A,
                        cot D/2 = - (a2 + b2 + c2)/(12*area)

Trilinears        g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = 3 sin A - cos A cot ω   (Peter J. C. Moses, 7/20/03)

Trilinears        h(A,B,C) : h(B,C,A) : h(C,A,B), where h(A,B,C) = cos A - 3 sin A tan ω   (Peter J. C. Moses, 8/22/03)

Barycentrics  (sin A)f(A,B,C): (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(576) = X(3) - 3X(6)

X(576) lies on these lines: 3,6   4,542   5,524   23,184   140,597   262,385

X(576) = reflection of X(I) in X(J) for these (I,J): (3,575), (182,6)
X(576) = inverse-in-Brocard-circle of X(575)
X(576) = inverse-in-2nd-Lemoine-circle of X(1691)


X(577) = HARMONIC OF X(216)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin A cos2A     (M. Iliev, 4/12/07)
Barycentrics  (sin A)f(A,B,C): (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(577) lies on these lines: 2,95   3,6   20,393   22,232   30,53   48,603   69,248   112,376   141,441   160,206   172,1038   184,418   198,478   219,906   220,268   264,401   395,466   396,465

X(577) = inverse-in-Brocard-circle of X(216)
X(577) = complement of X(317)
X(577) = X(I)-Ceva conjugate of X(J) for these (I,J): (3,184), (97,3)
X(577) = X(418)-cross conjugate of X(3)
X(577) = crosspoint of X(I) and X(J) for these (I,J): (2,68), (3,394)
X(577) = crosssum of X(I) and X(J) for these (I,J): (4,393), (6,24), (324,467)
X(577) = crossdifference of every pair of points on line X(403)X(523)


X(578) = ORTHOHARMONIC OF X(216)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin A + cot D/2 cos A,
                        cot D/2 = (a2b2c2 cos A cos B cos C)/[8*(area)3]

Barycentrics  (sin A)f(A,B,C): (sin B)f(B,C,A) : (sin C)f(C,A,B)

Joe Goggins notes (10/1/2008), in connection with the note at X(389), that trilinears for X(578) are sin(A-T) : sin(B-T) : sin(C-T), where tan(T) = - cot A cot B cot C.

X(578) lies on these lines: 2,1092   3,6   4,54   24,51   49,381   156,546   185,378   436,1093

X(578) = inverse-in-Brocard-circle of X(389)


X(579) = HARMONIC OF X(284)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a(a2b + a2c + abc - b3 - c3)      (M.Iliev, 5/13/07)

Barycentrics   af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(579) = s*X(3) - (r + 2R)*cot(ω)*X(6)

X(579) lies on these lines: 1,71   2,7   3,6   19,46   36,48   37,942   40,387   56,219   109,608   165,380   198,218   443,966   474,965   517,1108

X(579) = inverse-in-Brocard-circle of X(284)
X(579) = isogonal conjugate of X(1751)
X(579) = X(27)-Ceva conjugate of X(1)
X(579) = crosssum of X(11) and X(652)
X(579) = crossdifference of every pair of points on line X(523)X(663)


X(580) = ORTHOGONAL OF X(284)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin A + cot D/2 cos A,
                        cot D/2 = (e1 - e2 - 2abc)/[4*area*(a + b + c)], where e1, e2 are as for X(579)

Barycentrics  (sin A)f(A,B,C): (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(580) lies on these lines: 1,201   2,283   3,6   31,40   34,46   36,54   57,255   162,412   165,601   223,603   238,946   517,595

X(580) = inverse-in-Brocard-circle of X(581)
X(580) = X(270)-Ceva conjugate of X(1)
X(580) = crosspoint of X(59) and X(162)
X(580) = crosssum of X(11) and X(656)


X(581) = ORTHOHARMONIC OF X(284)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin A + cot D/2 cos A,
                        cot D/2 = (2abc - e1 + e2)/[4*area*(a + b + c)], where e1, e2 are as for X(579)

Barycentrics  (sin A)f(A,B,C): (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(581) lies on these lines: 1,4   3,6   35,47   40,42   81,411   84,941   222,1035   936,966   947,1036   995,1104

X(581) = inverse-in-Brocard-circle of X(580)
X(581) = crossdifference of every pair of points on line X(523)X(652)


X(582) = HARMONIC OF X(500)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sin A + cot D/2 cos A,
                        cot D/2 = (e1 - e2 - 4abc)/[4*area*(a + b + c)], where
                        e1 = a3 + b3 + c3
                        e2 = a2(b + c) + b2(c + a) + c2(a + b)

Barycentrics  (sin A)f(A,B,C): (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(582) lies on these lines: 3,6   212,942   283,474   517,602

X(582) = inverse-in-Brocard-circle of X(500)


X(583) = ORTHOGONAL OF X(500)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a(a2b + a2c + 2abc - b3 - c3)      (M.Iliev, 5/13/07)

Barycentrics   af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(583) = s*X(3) + (r - 3R)*cot(ω)*X(6)

X(583) lies on these lines: 3,6   37,38   44,992   71,1100   518,1009

X(583) = inverse-in-Brocard-circle of X(584)


X(584) = ORTHOHARMONIC OF X(500)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a(ab2 + ac2 + bc2 + b2c + 2abc - a3)      (M.Iliev, 5/13/07)

Barycentrics   af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(584) = s*X(3) + (r + 3R)*cot(ω)*X(6)

X(584) lies on these lines: 3,6   37,41   42,560   48,354

X(584) = inverse-in-Brocard-circle of X(583)


X(585) = 1st CONGRUENT SHRUNK INSQUARES POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [2*area*(1/b + 1/c - 1/a) + b + c - a]/a
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = 2*area*(1/b + 1/c - 1/a) + b + c - a

X(585) lies on this line: 8,192

For a discussion, see Floor van Lamoen, "Vierkanten in een driehoek: 5. Gekrompen ingeschreven vierkanten"


X(586) = 2nd CONGRUENT SHRUNK INSQUARES POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [2*area*(1/b + 1/c - 1/a) + a - b - c]/a
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = 2*area*(1/b + 1/c - 1/a) + a - b - c

X(586) lies on this line: 8,192

For a discussion, see Floor van Lamoen, "Vierkanten in een driehoek: 5. Gekrompen ingeschreven vierkanten"


X(587) = POINT ARCTURUS

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc[2(a + b + c) + (a - b - c) tan A]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = 2(a + b + c) + (a - b - c) tan A

X(587) lies on this line: 2,92


X(588) = 1st KENMOTU-VAN LAMOEN POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a/(a2 + 4*area(ABC))
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(588) is the perspector of triangles ABC and A'B'C', where A' is the circumcenter of X(371) and the points where the squares in the Kenmotu configuration with center X(371) meet sideline BC, and B' and C' are defined cyclically. See

Floor van Lamoen, Some concurrences from Tucker hexagons, Forum Geometricorum 2 (2002) 5-13.

X(588) is the homothetic center of triangle ABC and the Lucas(2:1) homothetic triangle; see X(371) and X(589). (Randy Hutson, 9/23/2011)

X(588) lies on this line: 39,589

X(588) = isogonal conjugate of X(590)
X(588) = cevapoint of X(6) and X(371)
X(588) = X(1994)-cross conjugate of X(589)


X(589) = 2nd KENMOTU-VAN LAMOEN POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a/(a2 - 4*area(ABC))
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(589) is the perspector of triangles ABC and A'B'C', where A' is the circumcenter of X(372) and the points where the squares in the Kenmotu configuration with center X(372) meet sideline BC, and B' and C' are defined cyclically. See the reference at X(588).

X(588) is the homothetic center of triangle ABC and the Lucas(-2:1) homothetic triangle; see X(371) and X(588). (Randy Hutson, 9/23/2011)

X(589) lies on this line: 39,588

X(589) = isogonal conjugate of X(615)
X(589) = cevapoint of X(6) and X(372)
X(589) = X(1994)-cross conjugate of X(588)


X(590) = ISOGONAL CONJUGATE OF X(588)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (a2 + 4*area(ABC))/a
                        = sin A + 2 sin B sin C : sin B + 2 sin C sin A : sin C + 2 sin A sin B
                        = aR + bc : bR + ca : cR + ab

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(590) lies on these lines: 1,3302   2,6   3,485   4,1151   5,371   11,2066   12,2067   17,3389   32,640   39,642   53,1585   140,372   157,3155   393,3535   397,2045   398,2046   486,1656   493,2165   498,1335   499,1124   588,2963   605,748   606,750   631,1152   639,1504   1131,3522   1327,3534   1578,3546   1579,3547   1583,1609   1588,3090   1834,2047   3085,3298   3086,3297   3087,3536   3092,3542   3093,3541   3312,3526   3525,3594

X(590) = isogonal conjugate of X(588)
X(590) = complement of X(492)
X(590) = crosspoint of X(2) and X(485)
X(590) = crosssum of X(6) and X(371)


X(591) = 1st VAN LAMOEN PERPENDICULAR BISECTORS POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc[b2 + c2 - 2a2 + 4*area(ABC)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

Erect squares outwardly on the sides of triangle ABC. Two edges emanate from A; let P and Q be their endpoints. Let a' be the perpendicular bisector of PQ, and define b' and c' cyclically. Then a', b', c' concur in X(591). See also X(1991). (Floor van Lamoen, 1/4/01, Hyacinthos #2123)

If you have The Geometer's Sketchpad, you can view 1st Van Lamoen Perpendicular Bisectors Point.

X(591) lies on these lines: 2,6   372,754   488,3071   637,1152

X(591) = reflection of X(1991) in X(2)


X(592) = VAN LAMOEN CIRCUMCENTERS POINT

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/[cos A + 2 cos(B - ω) cos(C - ω)]
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = (sin A)f(A,B,C)

Let P be the point where the line through X(6) parallel to line CA meets line BC, and let Q be the point where the line through X(6) parallel to line AB meets line BC. Let X = X(182), and let A' be the circumcenter of the triangle PQX. Define B' and C' cyclically. The lines AA', BB', CC' concur in X(592). (Floor van Lamoen, 1/4/01)


X(593) = 1st HATZIPOLAKIS-YIU POINT

Trilinears        a/(b + c)2 : b/(c + a)2 : c/(a + b)2
Barycentrics  [a/(b + c)]2 : [b/(c + a)]2 : [c/(a + b)]2

Let O(A) be the circle tangent to line BC and to the circumcircle of triangle ABC at vertex A. Let AB and AC be where O(A) meets lines AB and AC, respectively. Let L(A) be the line joining AB and AC, and define L(B) and L(C) cyclically. Let A' be where L(B) and L(C) meet, and define B' and C' cyclically. Then triangle A'B'C' is homothetic to triangle ABC, and the center of homothety is X(593).

X(593) lies on these lines: 2,261   31,110   36,58   81,757   115,1029   229,1104

X(593) = isogonal conjugate of X(594)

(Antreas Hatzipolakis, Paul Yiu, Hyacinthos #2070)


X(594) = ISOGONAL CONJUGATE OF X(593)

Trilinears        (b + c)2/a : (c + a)2/b : (a + b)2/c
Barycentrics  (b + c)2 : (c + a)2 : (a + b)2

X(594) lies on these lines: 6,8   7,599   9,80   10,37   45,346   53,318   75,141   100,1030   210,430   220,281   313,321   319,524   519,1100   572,952   762,1089

X(594) = midpoint of X(319) and X(894)
X(594) = isogonal conjugate of X(593)
X(594) = crosspoint of X(10) and X(321)
X(594) = crosssum of X(I) and X(J) for these (I,J): (6,595), (58,1333)


X(595) = 2nd HATZIPOLAKIS-YIU POINT

Trilinears        a(a2 + ab + ac - bc) : b(b2 + bc + ba - ca) : c(c2 + ca + cb - ab)
Trilinears        sa2 - SR : sb2 - SR : sc2 - SR
Barycentrics  a2(a2 + ab + ac - bc) : b2(b2 + bc + ba - ca) : c2(c2 + ca + cb - ab)

Let O(A) be the circle tangent to line BC and to the circumcircle of triangle ABC at vertex A, and define O(B) and O(C) cyclically. X(595) is the radical center of O(A), O(B), O(C).

X(595) lies on these lines: 1,21   3,995   10,82   32,101   35,902   40,602   46,614   55,386   56,106   110,849   171,1125   387,390   517,580

X(595) = isogonal conjugate of X(596)
X(595) = crosssum of X(244) and X(523)

(Antreas Hatzipolakis, Paul Yiu, Hyacinthos #2070)

X(596) = ISOGONAL CONJUGATE OF X(595)

Trilinears        1/[a(a2 + ab + ac - bc)] : 1/[b(b2 + bc + ba - ca)] : 1/[c(c2 + ca + cb - ab)]
Barycentrics  1/(a2 + ab + ac - bc) : 1/(b2 + bc + ba - ca) : 1/(c2 + ca + cb - ab)

X(596) lies on these lines: 10,38   37,39   58,82   65,519   244,1089

X(596) = isogonal conjugate of X(595)


X(597) = MIDPOINT OF X(2) AND X(6)

Trilinears        (4a2 + b2 + c2)/a : (4b2 + c2 + a2)/b : (4c2 + a2 + b2)/c
Barycentrics  4a2 + b2 + c2 : 4b2 + c2 + a2 : 4c2 + a2 + b2

X(597) is the circumcenter of the pedal triangle of X(I) for these I: 2, 6

X(597) lies on these lines: 2,6   5,542   30,182   39,1084   83,671   140,576   511,549   518,551

X(597) = midpoint of X(2) and X(6)
X(597) = reflection of X(141) in X(2)
X(597) = complement of X(599)
X(597) = crosssum of X(6) and X(574)

(Bernard Gibert, 1/5/01, Hyacinthos #2334)


X(598) = ISOGONAL CONJUGATE OF X(574)

Trilinears        bc/(a2 - 2b2 - 2c2) : ca/(b2 - 2c2 - 2a2) : ab/(c2 - 2a2 - 2b2)
Barycentrics  1/(a2 - 2b2 - 2c2) : 1/(b2 - 2c2 - 2a2) : 1/(c2 - 2a2 - 2b2)

The Lemoine ellipse is the ellipse inscribed in triangle ABC having X(2) and X(6) as foci. Let A' be where this ellipse meets sideline BC, and define B' and C' cyclically. Then triangles ABC and A'B'C' are perspective, and their perspector is X(598). (Bernard Gibert, 1/5/01, Hyacinthos #2334)

X(598) lies on these lines: 2,187   4,575   6,671   30,262   76,524   98,381

X(598) = isogonal conjugate of X(574)
X(598) = isotomic conjugate of X(599)


X(599) = ISOTOMIC CONJUGATE OF X(598)

Trilinears        bc(a2 - 2b2 - 2c2) : ca(b2 - 2c2 - 2a2) : ab(c2 - 2a2 - 2b2)
Barycentrics  a2 - 2b2 - 2c2 : b2 - 2c2 - 2a2 : c2 - 2a2 - 2b2

X(599) lies on these lines: 2,6   3,67   7,594   8,1086   76,338   340,458   381,511

X(599) = midpoint of X(2) and X(69)
X(599) = reflection of X(I) in X(J) for these (I,J): (2,141), (6,2)
X(599) = isogonal conjugate of X(1383)
X(599) = isotomic conjugate of X(598)
X(599) = complement of X(1992)
X(599) = anticomplement of X(597)
X(599) = crosssum of X(6) and X(1384)

(Bernard Gibert, 1/5/01, Hyacinthos #2334)


X(600) = 3rd HATZIPOLAKIS-YIU POINT

Barycentrics   f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a2(bc + 2S)[abc(b + c - a) + 2(b2 + c2 - a2)S]

Let OA be the circle with center A and radius R, the circumradius of triangle ABC. Let BA be the point where OA meets line AB farthest from B. Define CB and AC cyclically. Let CA be the point where OA meets line AC farthest from C. Define AB and BC cyclically. X(600) is the radical center of the circles ABACA, BCBAB, CACBC. If "farthest from" is changed to "nearest to" in the construction, the resulting point is X(5507). (Antreas Hatzipolakis, Paul Yiu, 1/5/01, Hyacinthos #2344, #2346-8; for a correction in coordinates, see Paul Yiu, Adgeom #202.)

If you have The Geometer's Sketchpad, you can view X(600).


X(601) = INTERSECTION OF LINES X(3)X(31) AND X(55)X(255)

Trilinears        sin2A + cos A : sin2B + cos B : sin2C + cos C
Barycentrics  (sin A)(sin2A + cos A) : (sin B)(sin2B + cos B) : (sin C)(sin2C + cos C)

X(601) lies on these lines: 1,104   3,31   4,171   5,750   35,47   40,58   41,906   55,255   140,748   165,580   201,920   371,606   372,605   774,1060   912,976   999,1106


X(602) = INTERSECTION OF LINES X(3)X(31) AND X(56)X(255)

Trilinears        sin2A - cos A : sin2B - cos B : sin2C - cos C
Barycentrics  (sin A)(sin2A - cos A) : (sin B)(sin2B - cos B) : (sin C)(sin2C - cos C)

X(602) lies on these lines: 1,201   3,31   4,238   5,748   36,47   40,595   56,255   140,750   171,631   371,605   372,606   517,582   774,1062


X(603) = X(58)-CEVA CONJUGATE OF X(56)

Trilinears        cos2A - cos A : cos2B - cos B : cos2C - cos C
Barycentrics  (sin A)(cos2A - cos A) : (cos B)(cos2B - cos B) : (cos C)(cos2C - cos C)

X(603) lies on these lines: 1,104   3,73   6,1035   12,750   28,34   31,56   33,84   36,47   41,911   48,577   63,201   77,283   171,388   223,580   404,651

X(603) = isogonal conjugate of X(318)
X(603) = X(I)-Ceva conjugate of X(J) for these (I,J): (58,56), (222,48)
X(603) = X(184)-cross conjugate of X(48)
X(603) = crosspoint of X(57) and X(77)
X(603) = crosssum of X(I) and X(J) for these (I,J): (1,1158), (9,33)


X(604) = X(56)-CEVA CONJUGATE OF X(31)

Trilinears        a(1 - cos A) : b(1 - cos B) : c(1 - cos C)
Trilinears        a2(SA - bc) : b2(SB - ca) : c2(SC - ab)
Barycentrics   a2(1 - cos A) : b2(1 - cos B) : c2(1 - cos C)

X(604) lies on these lines: 1,572   6,41   19,909   31,184   32,1106   36,573   57,77   65,1100   109,739   219,672   608,1042

X(604) = isogonal conjugate of X(312)
X(604) = X(56)-Ceva conjugate of X(31)
X(604) = X(32)-cross conjugate of X(31)
X(604) = crosspoint of X(34) and X(57)
X(604) = crosssum of X(I) and X(J) for these (I,J): (2,329), (8,346), (9,78), (306,321)


X(605) = INTERSECTION OF LINES X(371)X(602) AND X(372)X(601)

Trilinears        a(1 + sin A) : b(1 + sin B) : c(1 + sin c)
Trilinears        a2(S + bc) : b2(S + ca) : c2(S + ab)
Barycentrics  a2(1 + sin A) : b2(1 + sin B) : c2(1 + sin C)

X(605) lies on these lines: 6,31   371,602   372,601   590,748   615,750


X(606) = INTERSECTION OF LINES X(371)X(601) AND X(372)X(602)

Trilinears        a(1 - sin A) : b(1 - sin B) : c(1 - sin c)
Trilinears        a2(S - bc) : b2(S - ca) : c2(S - ab)
Barycentrics  a2(1 - sin A) : b2(1 - sin B) : c2(1 - sin C)

X(606) lies on these lines: 6,31   371,601   372,602   590,750   615,748


X(607) = ISOGONAL CONJUGATE OF X(348)

Trilinears        a(1 + sec A) : b(1 + sec B) : c(1 + sec c)
Barycentrics  a2(1 + sec A) : b2(1 + sec B) : c2(1 + sec C)

X(607) lies on these lines: 1,949   4,218   6,19   8,29   9,1039   25,41   28,1002   33,210   56,911   92,239   213,1096   227,910   240,611

X(607) is the {X(6),X(19)}-harmonic conjugate of X(608). For a list of other harmonic conjugates of X(607), click Tables at the top of this page.

X(607) = isogonal conjugate of X(348)
X(607) = X(I)-Ceva conjugate of X(J) for these (I,J): (19,25), (281,55)
X(607) = X(213)-cross conjugate of X(41)
X(607) = crosspoint of X(19) and X(33)
X(607) = crosssum of X(I) and X(J) for these (I,J): (2,347), (63,77), (307,1214)


X(608) = ISOGONAL CONJUGATE OF X(345)

Trilinears        a(1 - sec A) : b(1 - sec B) : c(1 - sec c)
Barycentrics  a2(1 - sec A) : b2(1 - sec B) : c2(1 - sec C)

X(608) lies on these lines: 6,19   7,27   9,1041   25,31   28,959   92,894   108,739   109,579   193,651   223,380   240,613   571,913   604,1042

X(608) is the {X(6),X(19)}-harmonic conjugate of X(607). For a list of other harmonic conjugates of X(608), click Tables at the top of this page.

X(608) = isogonal conjugate of X(345)
X(608) = X(I)-Ceva conjugate of X(J) for these (I,J): (34,25), (278,56)
X(608) = crosssum of X(219) and X(1259)


X(609) = INTERSECTION OF LINES X(1)X(32) AND X(6)X(36)

Trilinears        area + a2 sin A : area + b2 sin B : area + c2 sin C
Barycentrics  a(area + a2 sin A) : b(area + b2 sin B) : c(area + c2 sin C)

X(609) lies on these lines: 1,32   6,36   31,101   33,112   41,58   251,614   995,1055


X(610) = X(63)-CEVA CONJUGATE OF X(1)

Trilinears        area - a2 cot A : area - b2 cot B : area - c2 cot C
                        = tan B + tan C - tan A : tan C + tan A - tan B : tan A + tan B - tan C    (Randy Hutson, 9/23/2011)
                        = SBSC - a2SA : SCSA - b2SB : SASB - c2SC    (C. Lozada, 9/07/2013)

Barycentrics  a(area - a2 cot A) : b(area - b2 cot B) : c(area - c2 cot C)

X(610) lies on these lines: 1,19   3,9   6,57   40,219   71,165   159,197   169,572   281,515   326,662

X(610) = isogonal conjugate of X(2184)
X(610) = X(63)-Ceva conjugate of X(1)
X(610) = X(204)-cross conjugate of X(1)


X(611) = INTERSECTION OF LINES X(1)X(6) AND X(55)X(511)

Trilinears        W + sin A : W + sin B : W + sin C, where W = (a2 + b2 + c2)/(4*area)
Barycentrics  a(W + sin A) : b(W + sin B) : c(W + sin C)

X(611) lies on these lines: 1,6   55,511   56,182   141,498   240,607   394,612


X(612) = INTERSECTION OF LINES X(1)X(2) AND X(9)X(31)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a2 + b2 + c2 + 2bc      (M. Iliev, 5/13/2007)
Trilinears        bc + Sω : ca + Sω : ab + Sω      (C. Lozada, 9/07/2013)
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(612) is the homothetic center of the incentral triangle and the Ayme triangle; see X(3610).

X(612) lies on these lines: 1,2   6,210   9,31   12,34   19,25   21,989   22,35   38,57   63,171   165,990   394,611   404,988   495,1060   518,940

X(612) = crossdifference of every pair of points on line X(649)X(905)


X(613) = INTERSECTION OF LINES X(1)X(6) AND X(56)X(511)

Trilinears        W - sin A : W - sin B : W - sin C, where W = (a2 + b2 + c2)/(4*area)
Barycentrics  a(W - sin A) : b(W - sin B) : c(W - sin C)

X(613) lies on these lines: 1,6   55,182   56,511   141,499   222,982   240,608   394,614   496,1069


X(614) = INTERSECTION OF LINES X(1)X(2) AND X(11)X(33)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a2 + b2 + c2 - 2bc      (M. Iliev, 5/13/07)
Trilinears        bc - Sω : ca - Sω : ab - Sω      (C. Lozada, 9/07/2013)
Barycentrics  af(a,b,c) : bf(b,c,a) : cf(c,a,b)

X(614) lies on these lines: 1,2   6,354   9,38   11,33   21,988   22,36   25,34   31,57   46,595   63,238   106,998   165,902   251,609   269,479   278,1096   305,350   394,613   496,1062   497,1040   968,1001   1616,3057

X(614) = crosspoint of X(I) and X(J) for these (I,J): (1,269), (28,86)
X(614) = crosssum of X(42) and X(72)


X(615) = ISOGONAL CONJUGATE OF X(589)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (a2 - 4*area)/a
                        = g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin A - 2 sin B sin C
                        aR - bc : bR - ca : cR - ab

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = a2 - 4*area

X(615) lies on these lines: 2,6   3,486   5,372   32,639   39,641   140,371   605,750   606,748

X(615) = isogonal conjugate of X(589)
X(615) = complement of X(491)
X(615) = crosspoint of X(2) and X(486)
X(615) = crosssum of X(6) and X(372)



leftri Centers 616- 642 rightri
were contributed by Bernard Gibert, March 2, 2001. Notation:

SA = (b2 + c2 - a2)/2       SB = (c2 + a2 - b2)/2       SC = (a2 + b2 - c2)/2


Joe Goggins (Oct. 19, 2005) found trilinears for points in this section, using the following notation. Let

F(13) = a csc(A + π/3) + b csc(B + π/3) + c csc(C + π/3)
F(14) = a csc(A - π/3) + b csc(B - π/3) + c csc(C - π/3)
These are based on trilinears for the isogonic centers, X(13) and X(14). In like manner, F(I) is defined for I = 15, 16, 17, 18, 61, 62.

Using this notation, we have, for example,
X(616) = F(13)/a - 2 csc(A + π/3) : F(13)/b - 2 csc(B + π/3) : F(13)/c - 2 csc(C + π/3)
X(617) = F(14)/a - 2 csc(A - π/3) : F(14)/b - 2 csc(B - π/3) : F(14)/c - 2 csc(C - π/3)

Trilinears of this sort are given below at X(I) for these I: 616-619, 621-624, 627-630, and 633-636.
underbar

X(616) = ANTICOMPLEMENT OF X(13)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [SBSC - 2SA(a2 + sqr(3) area)]/a

Trilinears        F(13)/a - 2 csc(A + π/3) : F(13)/b - 2 csc(B + π/3) : F(13)/c - 2 csc(C + π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(616) = X(13)-of-anticomplementary-triangle

The midpoint of X(616) and X(617) is the Steiner point, X(99).

X(616) lies on the Neuberg cubic and these lines: 2,13   3,299   4,627   14,148   15,532   20,633   30,298   69,74   302,381   303,549   489,2043   490,2044

X(616) = reflection of X(I) in X(J) for these (I,J): (13,618), (148,14), (617,99), (621,298)
X(616) = isogonal conjugate of X(3440)
X(616) = anticomplement of X(13)
X(616) = anticomplementary conjugate of X(621)
X(616) = X(298)-Ceva conjugate of X(2)


X(617) = ANTICOMPLEMENT OF X(14)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [SBSC - 2SA(a2 - sqr(3) area)]/a

Trilinears        F(14)/a - 2 csc(A - π/3) : F(14)/b - 2 csc(B - π/3) : F(14)/c - 2 csc(C - π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(617) lies on the Neuberg cubic and these lines: 2,14   3,298   4,628   13,148   16,533   20,634   30,299   69,74   302,549   303,381

X(617) = reflection of X(I) in X(J) for these (I,J): (14,619), (148,13), (616,99), (622,299)
X(617) = isogonal conjugate of X(3441)
X(617) = anticomplement of X(14)
X(617) = anticomplementary conjugate of X(622)
X(617) = X(299)-Ceva conjugate of X(2)


X(618) = COMPLEMENT OF X(13)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = [2SBSC + 5SAa2 + 2 sqr(3)(b2 + c2) area]/a

Trilinears        F(13)/a - csc(A + π/3) : F(13)/b - csc(B + π/3) : F(13)/c - csc(C + π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(618) lies on these lines: 2,13   3,635   5,629   14,99   15,298   30,623   39,395   61,627   140,630   141,542   396,532

X(618) = X(13)-of-medial-triangle

X(618) = midpoint of X(I) and X(J) for these (I,J): (13,616), (14,99), (15,298)
X(618) = reflection of X(619) in X(620)
X(618) = complementary conjugate of X(623)
X(618) = X(2)-Ceva conjugate of X(396)
X(618) = crosspoint of X(2) and X(298)


X(619) = COMPLEMENT OF X(14)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = [2SBSC + 5SAa2 - 2 sqr(3) (b2 + c2) area]/a

Trilinears        F(14)/a - csc(A - π/3) : F(14)/b - csc(B - π/3) : F(14)/c - csc(C - π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(619) lies on these lines:
2,14   3,636   5,630   13,99   16,299   30,624   39,396   62,628   140,629   141,542   395,533

X(619) = midpoint of X(I) and X(J) for these (I,J): (13,99), (14,617), (16,299)
X(619) = reflection of X(618) in X(620)
X(619) = complementary conjugate of X(624)
X(619) = X(2)-Ceva conjugate of X(395)
X(619) = crosspoint of X(2) and X(299)


X(620) = MIDPOINT OF X(618) AND X(619)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [4SAa2 - (b4 + c4)]/a
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

Let S = X(99). Let A' be the centroid of the triangle BCS, and define B' and C' cyclically. Let D' be the centroid of ABC. The four centroids form a quadrilateral homothetic to the quadrilateral ABCS. The center of homothety is X(620), which is the centroid of ABCS. (Randy Hutson, 9/23/2011)

X(620) lies on these lines:
2,99   3,114   30,625   98,631   141,542   187,325   230,538

X(620) = midpoint of X(I) and X(J) for these (I,J): (3,114), (99,115), (187,325), (618,619)
X(620) = complement of X(115)


X(621) = ANTICOMPLEMENT OF X(15)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [sqr(3) SBSC + 2SA area]/a

Trilinears        F(15)/a - 2 sin(A + π/3) : F(15)/b - 2 sin(B + π/3) : F(15)/c - 2 sin(C + π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(621) lies on these lines: 2,14   3,302   4,69   5,303   13,533   20,627   30,298   183,383   265,300   299,381   325,1080   343,472   394,473

X(621) = reflection of X(I) in X(J) for these (I,J): (15,623), (616,298), (622,316)
X(621) = isogonal conjugate of X(3438)
X(621) = isotomic conjugate of X(2992)
X(621) = anticomplement of X(15)
X(621) = anticomplementary conjugate of X(616)
X(621) = X(300)-Ceva conjugate of X(2)


X(622) = ANTICOMPLEMENT OF X(16)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [sqr(3) SBSC - 2SA area]/a

Trilinears        F(16)/a - 2 sin(A - π/3) : F(16)/b - 2 sin(B - π/3) : F(16)/c - 2 sin(C - π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(622) lies on these lines: 2,13   3,303   4,69   5,302   14,532   20,628   30,299   183,1080   265,301   298,381   325,383   343,473   394,472

X(622) = reflection of X(I) in X(J) for these (I,J): (16,624), (617,299), (621,316)
X(622) = isogonal conjugate of X(3439)
X(622) = isotomic conjugate of X(2993)
X(622) = anticomplement of X(16)
X(622) = anticomplementary conjugate of X(617)
X(622) = X(301)-Ceva conjugate of X(2)


X(623) = COMPLEMENT OF X(15)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = [2(b2 + c2) area + sqr(3) (SAa2 + 2SBSC)]/a

Trilinears        F(15)/a - sin(A + π/3) : F(15)/b - sin(B + π/3) : F(15)/c - sin(C + π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(623) lies on these lines: 2,14   3,629   5,141   13,298   16,302   17,633   18,83   30,618   396,533

X(623) = midpoint of X(I) and X(J) for these (I,J): (13,298), (15,621), (16,316)
X(623) = reflection of X(624) in X(625)
X(623) = inverse-in-nine-point-circle of X(624)
X(623) = complement of X(15)
X(623) = complementary conjugate of X(618)
X(623) = crosspoint of X(2) and X(300)


X(624) = COMPLEMENT OF X(16)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = [2(b2 + c2) area - sqr(3)(a2SA + 2SBSC)]/a

Trilinears        F(16)/a - sin(A - π/3) : F(16)/b - sin(B - π/3) : F(16)/c - sin(C - π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(624) lies on these lines: 2,13   3,630   5,141   14,299   15,303   17,83   30,619   395,532

X(624) = midpoint of X(I) and X(J) for these (I,J): (14,299), (15,316), (16,622)
X(624) = reflection of X(623) in X(625)
X(624) = inverse-in-nine-point-circle of X(623)
X(624) = complement of X(16)
X(624) = complementary conjugate of X(619)
X(624) = crosspoint of X(2) and X(301)


X(625) = MIDPOINT OF X(623) AND X(624)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [2(b4 + c4 - b2c2) - a2(b2 + c2)]/a
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(625) lies on these lines: 2,187   5,141   30,620   115,325   126,858   230,754

X(625) = midpoint of X(I) and X(J) for these (I,J): (115,325), (187,316), (623,624)
X(625) = inverse-in-nine-point-circle of X(141)
X(625) = complement of X(187)


X(626) = COMPLEMENT OF X(32)

Trilinears        (b4 + c4)/a : (c4 + a4)/b: (a4 + b4)/c
Barycentrics  b4 + c4 : c4 + a4 : a4 + b4

X(626) lies on these lines: 2,32   3,114   5,141   10,760   37,746   39,325   76,115   316,384

X(626) = midpoint of X(I) and X(J) for these (I,J): (32,315), (639,640)
X(626) = complement of X(32)
X(626) = complementary conjugate of X(39)
X(626) = X(301)-Ceva conjugate of X(2)


X(627) = ANTICOMPLEMENT OF X(17)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [SBSC + 2SA(a2 + sqr(3) area)]/a

Trilinears        F(17)/a - 2 sec(A - π/3) : F(17)/b - 2 sec(B - π/3) : F(17)/c - 2 sec(C - π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

Erect equilateral triangles outwards on the sides of triangle ABC; the circumcenter of the apices is X(627). (Peter Moses, 7/16,2003)

X(627) lies on the Napoleon cubic and these lines: 2,17   3,298   4,616   5,302   16,635   20,621   54,69   61,618   140,299

X(627) = reflection of X(17) in X(629)
X(627) = isogonal conjugate of X(3489)
X(627) = anticomplement of X(17)
X(627) = anticomplementary conjugate of X(633)
X(627) = X(I)-Ceva conjugate of X(J) for these (I,J): (5,628), (302,2)


X(628) = ANTICOMPLEMENT OF X(18)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [SBSC + 2SA(a2 - sqr(3) area)]/a

Trilinears        F(18)/a + 2 sec(A + π/3) : F(18)/b + 2 sec(B + π/3) : F(18)/c + 2 sec(C + π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

Erect equilateral triangles inwards on the sides of triangle ABC; the circumcenter of the apices is X(628). (Peter Moses, 7/16,2003)

X(628) lies on the Napoleon cubic and these lines: 2,18   3,299   4,617   5,303   15,636   20,622   54,69   62,619   140,298

X(628) = reflection of X(18) in X(630)
X(628) = isogonal conjugate of X(3490)
X(628) = anticomplement of X(18)
X(628) = anticomplementary conjugate of X(634)
X(628) = X(I)-Ceva conjugate of X(J) for these (I,J): (5,627), (303,2)


X(629) = COMPLEMENT OF X(17)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = [6SBSC + 7SAa2 + 2 sqr(3) (b2 + c2) area]/a

Trilinears        F(17)/a - sec(A - π/3) : F(17)/b - sec(B - π/3) : F(17)/c - sec(C - π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(629) lies on these lines: 2,17   3,623   5,618   61,302   140,619   141,575

X(629) = midpoint of X(17) and X(627)
X(629) = complement of X(17)
X(629) = complementary conjugate of X(635)
X(629) = crosspoint of X(2) and X(302)


X(630) = COMPLEMENT OF X(18)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where
                        f(a,b,c) = [6SBSC + 7SAa2 - 2 sqr(3) (b2 + c2) area]/a

Trilinears        F(18)/a + sec(A + π/3) : F(18)/b + sec(B + π/3) : F(18)/c + sec(C + π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(630) lies on these lines: 2,18   3,624   5,619   62,303   140,618   141,575

X(630) = midpoint of X(18) and X(628)
X(630) = complement of X(18)
X(630) = anticomplementary conjugate of X(636)
X(630) = crosspoint of X(2) and X(303)


X(631) = 3/5*OG

Trilinears        2 cos A + cos B cos C : 2 cos B + cos C cos A : 2 cos C + cos A cos B
                        = cos A + sin B sin C : cos B + sin C sin A : cos C + sin A sin B
                     = sec A + 2 sec B sec C : sec B + 2 sec C sec A : sec C + 2 sec A sec B

Barycentrics  (sin A)(2 cos A + cos B cos C) : (sin B)(2 cos B + cos C cos A) : (sin C)(2 cos C + cos A cos B)

X(631) lies on these lines: 1,1000   2,3   10,944   35,497   36,388   54,69   55,1058   56,1056   98,620   104,958   171,602   216,1075   238,601   315,1007   390,496   487,492   488,491   572,966   978,1064

X(631) is the {X(2),X(3)}-harmonic conjugate of X(4). For a list of other harmonic conjugates of X(631), click Tables at the top of this page.

X(631) = isogonal conjugate of X(3527)
X(631) = reflection of X(632) in X(140)
X(631) = inverse-in-orthocentroidal-circle of X(3090)
X(631) = complement of X(3091)
X(631) = anticomplement of X(1656)


X(632) = 9/10*OG

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (6SBSC + 7SAa2)/a
                     = 7 cos A + 6 cos B cos C : 7 cos B + 6 cos C cos A : 7 cos C + 6 cos A cos B

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(632) lies on these lines: 2,3   141,575

X(632) is the {X(2),X(140)}-harmonic conjugate of X(5). For a list of other harmonic conjugates of X(632), click Tables at the top of this page.

X(632) = reflection of X(631) in X(140)
X(632) = complement of X(1656)


X(633) = ANTICOMPLEMENT OF X(61)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (SBSC + 2 sqr(3) SA area)/a

Trilinears        F(61)/a - 2 cos(A - π/3) : F(61)/b - 2 cos(B - π/3) : F(61)/c - 2 cos(C - π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(633) lies on these lines: 2,18   3,298   4,69   5,299   14,636   17,623   20,616   140,302   141,398   343,471   394,470   397,524

X(633) = isogonal conjugate of X(3442)
X(633) = anticomplement of X(61)
X(633) = anticomplementary conjugate of X(627)


X(634) = ANTICOMPLEMENT OF X(62)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (SBSC - 2 sqr(3) SA area)/a

Trilinears        F(62)/a + 2 cos(A + π/3) : F(62)/b + 2 cos(B + π/3) : F(62)/c + 2 cos(C + π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(634) lies on these lines: 2,17   3,299   4,69   5,298   13,635   18,624   20,617   140,303   141,397   343,470   394,471   398,524

X(634) = reflection of X(I) in X(J) for these (I,J): (62,636), (61,635)
X(634) = isogonal conjugate of X(3443)
X(634) = anticomplement of X(62)
X(634) = anticomplementary conjugate of X(628)


X(635) = COMPLEMENT OF X(61)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [2SBSC + SAa2 + 2 sqr(3) (b2 + c2) area]/a

Trilinears        F(61)/a - cos(A - π/3) : F(61)/b - cos(B - π/3) : F(61)/c - cos(C - π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(635) lies on these lines: 2,18   3,618   5,141   13,634   16,627   17,299   62,298   140,619   397,532

X(635) = midpoint of X(61) and X(633)
X(635) = complement of X(61)
X(635) = complementary conjugate of X(629)


X(636) = COMPLEMENT OF X(62)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [2SBSC + SAa2 - 2 sqr(3) (b2 + c2) area]/a

Trilinears        F(62)/a + cos(A + π/3) : F(62)/b + cos(B + π/3) : F(62)/c + cos(C + π/3)

Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(636) lies on these lines: 2,17   3,619   5,141   14,633   15,628   18,298   61,299   140,618   398,533

X(636) = midpoint of X(62) and X(634)
X(636) = complement of X(62)
X(636) = complementary conjugate of X(630)


X(637) = ANTICOMPLEMENT OF X(371)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (SBSC + 2SA area)/a
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(637) lies on these lines: 2,371   3,489   4,69   5,491   20,488   30,490

X(637) = reflection of X(I) in X(J) for these (I,J): (371,639), (638,315)
X(637) = anticomplement of X(371)
X(637) = anticomplementary conjugate of X(488)


X(638) = ANTICOMPLEMENT OF X(372)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (SBSC - 2SA area)/a
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(638) lies on these lines: 2,372   3,490   4,69   5,492   20,487   30,489

X(638) = reflection of X(I) in X(J) for these (I,J): (372,640), (637,315)
X(638) = anticomplement of X(372)
X(638) = anticomplementary conjugate of X(487)


X(639) = COMPLEMENT OF X(371)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [2SBSC + SAa2 + 2(b2 + c2) area]/a

Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = 2 + sin 2B + sin 2C - cos 2B - cos 2C
                        h(a,b,c) : h(b,c,a) : h(c,a,b), where h(a,b,c) = (a2 + 4 area(ABC))(b2 + c2) - (b2 - c2)2

X(639) lies on these lines: 2,371   3,641   5,141   32,615   69,485   315,372

X(639) = midpoint of X(I) and X(J) for these (I,J): (315,372), (371,637)
X(639) = reflection of X(640) in X(626)
X(639) = complement of X(371)
X(639) = complementary conjugate of X(641)


X(640) = COMPLEMENT OF X(372)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [2SBSC + SAa2 - 2(b2 + c2) area]/a
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(640) lies on these lines: 2,372   3,642   5,141   69,486   315,371

X(640) = midpoint of X(I) and X(J) for these (I,J): (315,371), (372,638)
X(640) = reflection of X(639) in X(626)
X(640) = complement of X(372)
X(640) = complementary conjugate of X(642)


X(641) = COMPLEMENT OF X(485)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [2SBSC + 3SAa2 + 2(b2 + c2) area]/a
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

Erect squares outwards on the sides of triangle ABC; the circumcenter of the centers of the squares is X(641). (Peter Moses, 7/16,2003)

X(641) lies on these lines: 2,372   3,639   39,615   140,141   371,492

X(641) = midpoint of X(485) and X(488)
X(641) = complement of X(485)
X(641) = complementary conjugate of X(639)
X(641) = crosspoint of X(2) and X(492)


X(642) = COMPLEMENT OF X(486)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = [2SBSC + 3SAa2 - 2(b2 + c2) area]/a
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

Erect squares inwards on the sides of triangle ABC; the circumcenter of the centers of the squares is X(642). (Peter Moses, 7/16,2003)

X(642) lies on these lines: 2,371   3,640   140,141   372,491

X(642) = midpoint of X(486) and X(487)
X(642) = complement of X(486)
X(642) = complementary conjugate of X(640)
X(642) = crosspoint of X(2) and X(491)


X(643) = TRILINEAR MULTIPLIER FOR KIEPERT PARABOLA

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (b + c - a)/(b2 - c2)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(643) satisfies the equation X*(incircle) = Kiepert parabola, where * denotes trilinear multiplication, defined by
(u : v : w) * (x : y : z) = ux : vy : wz.

X(643) lies on these lines: 8,1098   99,109   100,110   101,931   162,190   163,1018   212,312   283,1043


X(644) = TRILINEAR MULTIPLIER FOR YFF PARABOLA

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (b + c - a)/(b - c)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(644) satisfies the equation X*(incircle) = Yff parabola, where * denotes trilinear multiplication, defined by
(u : v : w) * (x : y : z) = ux : vy : wz.

X(644) lies on these lines: 8,220   78,728  100,101   105,1083   145,218   190,651  219,346   645,646   666,668   813,932   934,1025

X(644) = reflection of X(I) in X(J) for these (I,J): (105,1083), (1280,1)
X(644) = X(190)-Ceva conjugate of X(100)
X(644) = crosssum of X(764) and X(1015)
X(644) = crossdifference of every pair of points on line X(244)X(1357)


X(645) = BARYCENTRIC MULTIPLIER FOR KIEPERT PARABOLA

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (b + c - a)/[a(b2 - c2)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = (b + c - a)/(b2 - c2)

X(645) satisfies the equation X*(incircle) = Kiepert parabola, where * denotes barycentric multiplication, defined by
(u : v : w) * (x : y : z) = ux : vy : wz (barycentric coordinates; see note at X(2)).

X(645) lies on these lines: 9,261   99,101   100,931   294,314   644,646   648,668   651,799   666,670


X(646) = BARYCENTRIC MULTIPLIER FOR YFF PARABOLA

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (b + c - a)/[a2(b - c)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = (b + c - a)/[a(b - c)]

X(646) satisfies the equation X*(incircle) = Yff parabola, where * denotes barycentric multiplication, defined by
(u : v : w) * (x : y : z) = ux : vy : wz (barycentric coordinates, see note at X(2)).

X(646) lies on this line: 190,668   644,645

X(646) = X(522)-cross conjugate of X(314)


X(647) = CROSSDIFFERENCE OF X(2) AND X(3)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a(b2 - c2)(b2 + c2 - a2)
                        = u(A,B,C) : u(B,C,A) : u(C,A,B), where u(A,B,C) = sin 2A sin(B - C)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(647) = point whose trilinears are coefficients for the Euler line.
X(647) = radical center of the circumcircle, nine-point center, and Brocard circle (Wilson Stothers, 3/13/2003)
X(647) is the perspector of triangle ABC and the tangential triangle of the Jerabek hyperbola. (Randy Hutson, 9/23/2011)

X(647) lies on these lines: 1,1021   2,850   50,654   111,842   184,878   187,237   230,231   441,525   520,652

X(647) = isogonal conjugate of X(648)
X(647) = complement of X(850)
X(647) = X(I)-Ceva conjugate of X(J) for these (I,J): (2,125), (107,51), (110,184), (112,6), (1304,1495)
X(647) = crosspoint of X(I) and X(J) for these (I,J): (2,110), (6,112), (107,275)

X(647) = crosssum of X(I) and X(J) for these (I,J): (1,1021), (2,525), (6,523), (110,112), (185,647), (216,520), (512,1196), (651,653), (850,1235)

X(647) = crossdifference of every pair of points on line X(2)X(3)
X(647) = orthojoin of X(125)


X(648) = TRILINEAR POLE OF EULER LINE

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a(b2 - c2)(b2 + c2 - a2)]
                        = u(A,B,C) : u(B,C,A) : u(C,A,B), where u(A,B,C) = csc 2A csc(B - C)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(648) is constructed as the pole of the Euler line L as follows: let A", B", C" be the points where L meets the sidelines BC, CA, AB of the reference triangle ABC. Let A', B', C' be the harmonic conjugates of A", B", C" with respect to {B,C}, {C,A}, {A,B}, respectively, The lines AA', BB', CC' concur in X(648).

X(648) lies on these lines:
4,452   6,264   27,903   94,275   95,216   99,112   107,110   108,931   132,147   155,1093   162,190   185,1105   193,317   232,385   249,687   250,523   297,340   447,519   645,668   651,823   653,662   925,933   1020,1021   1075,1092

X(648) = reflection of X(I) in X(J) for these (I,J): (287,6), (340,297), (1494,2)
X(648) = isogonal conjugate of X(647)
X(648) = isotomic conjugate of X(525)
X(648) = cevapoint of X(110) and X(112)
X(648) = X(I)-cross conjugate of X(J) for these (I,J): (6,250), (110,99), (112,107), (520,95), (523,264)


X(649) = CROSSDIFFERENCE OF X(1) and X(2)

Trilinears        a(b - c) : b(c - a) : c(a - b)

Barycentrics  a2(b - c) : b2(c - a) : c2(a - b)

X(649) is the perspector of triangle ABC and the tangential triangle of the conic that passes through the points A, B, C, X(1), and X(6). (Randy Hutson, 9/23/2011)

X(649) lies on these lines:
31,884   42,788   44,513   57,1024   89,1022   100,660   101,901   109,919   187,237   190,889   239,514   693,812

X(649) = reflection of X(I) in X(J) for these (I,J): (661,650), (663,667)
X(649) = isogonal conjugate of X(190)
X(649) = isotomic conjugate of X(1978)
X(649) = X(I)-Ceva conjugate of X(J) for these (I,J): (57,244), (100,42), (101,6), (109,31), (190,1)
X(649) = X(I)-cross conjugate of X(J) for these (I,J): (512,513), (649,665)
X(649) = crosspoint of X(I) and X(J) for these (I,J): (1,190), (6, 101), (57,109), (81,100)

X(649) = crosssum of X(I) and X(J) for these (I,J): (1,649), (2,514), (9,522), (37,513), (100,644), (101,1331), (440,525), (523,1213)

X(649) = crossdifference of every pair of points on line X(1)X(2)


X(650) = CROSSDIFFERENCE OF X(1) AND X(3)

Trilinears        cos B - cos C : cos C - cos A : cos A - cos B
                        = (b - c)(b + c - a) : (c - a)(c + a - b) : (a - b)(a + b - c)
Barycentrics  sin A (cos B - cos C) : sin B (cos C - cos A) : sin C (cos A - cos B)
                        = a(b - c)(b + c - a) : b(c - a)(c + a - b) : c(a - b)(a + b - c)

X(650) is the perspector of triangle ABC and the tangential triangle of the Feuerbach hyperbola. (Randy Hutson, 9/23/2011)

Let T1, T2, T3 denote the intouch, extouch,and incentral triangles. Let T4 be the side triangle of T2 and T3; T5 that of T3 and T1, and T6 that of T1 and T2. Then X(650) is the perspector of triangle ABC and T4, of ABC and T5, and of ABC and T6. (Randy Hutson, 9/23/2011)

X(650) lies on these lines:
2,693   44,513   55,884   100,919   230,231   241,514   521,1021   663,861

X(650) = midpoint of X(649) and X(661)
X(650) = isogonal conjugate of X(651)
X(650) = complement of X(693)
X(650) = X(I)-Ceva conjugate of X(J) for these (I,J): (2,11), (100,55), (101,37), (108,33)
X(650) = crosspoint of X(I) and X(J) for these (I,J): (2,100), (57, 108), (101,284), (514,522)

X(650) = crosssum of X(I) and X(J) for these (I,J): (1,650), (6,513), (9,521), (73,652), (101,109), (222,905), (226,514), (525,1211), (649,1201), (663,1200), (665,1362)

X(650) = crossdifference of every pair of points on line X(1)X(3)
X(650) = orthojoin of X(1521)


X(651) = TRILINEAR POLE OF LINE X(1)X(3)

Trilinears        1/(cos B - cos C) : 1/(cos C - cos A) : 1/(cos A - cos B)
                        = 1/[(b - c)(b + c - a)] : 1/[(c - a)(c + a - b)] : 1[(a - b)(a + b - c)]
Barycentrics  (sin A)/(cos B - cos C) : (sin B)/(cos C - cos A) : (sin C)/(cos A - cos B)
                        = a/[(b - c)(b + c - a)] : b/[(c - a)(c + a - b)] : c/[(a - b)(a + b - c)]

X(651) lies on these lines:
2,222   6,7   8,221   9,77   21,73   44,241   57,88   59,513   63,223   65,895   69,478   81,226   100,109   101,934   108,110   144,219   155,1068   190,644   193,608   218,279   255,411   287,894   329,394   404,603   500,943   514,655   645,799   648,823   978,1106

X(651) = isogonal conjugate of X(650)
X(651) = cevapoint of X(101) and X(109)
X(651) = X(I)-cross conjugate of X(J) for these (I,J): (6,59), (101,100), (513,7), (514,81), (521,77)
X(651) = crosssum of X(I) and X(J) for these (I,J): (647,661), (657,663)


X(652) = CROSSDIFFERENCE OF X(1) AND X(4)

Trilinears        sec B - sec C : sec C - sec A : sec A - sec B
Barycentrics  sin A (sec B - sec C) : sin B (sec C - sec A) : sin C (sec A - sec B)

X(652) is the perspector of triangle ABC and the tangential triangle of the conic that passes through the points A, B, C, X(1), and X(3). (Randy Hutson, 9/23/2011)

X(652) lies on these lines: 44,513   243,522   520,647

X(652) = isogonal conjugate of X(653)
X(652) = X(I)-Ceva conjugate of X(J) for these (I,J): (101,48), (109,55)
X(652) = crosspoint of X(I) and X(J) for these (I,J): (9,101), (109, 222)
X(652) = crosssum of X(I) and X(J) for these (I,J): (1,652), (57,514), (65,650), (281,522), (513,1108)
X(652) = crossdifference of every pair of points on line X(1)X(4)


X(653) = TRILINEAR POLE OF LINE X(1)X(4)

Trilinears        1/(sec B - sec C) : 1/(sec C - sec A) : 1/(sec A - sec B)
Barycentrics  (sin A)/(sec B - sec C) : (sin B)/(sec C - sec A) : (sin C)/(sec A - sec B)

X(653) lies on these lines:
2,196   7,281   9,342   19,273   29,65   46,158   57,92   78,207   88,278   100,108   107,109   208,318   225,897   648,662

X(653) = isogonal conjugate of X(652)
X(653) = X(I)-cross conjugate of X(J) for these (I,J): (514,92), (522,7)
X(653) = crosssum of X(647) and X(822)


X(654) = CROSSDIFFERENCE OF X(1) AND X(5)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = cos(A - B) - cos(C - A)
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin A f(A,B,C)

X(654) lies on these lines: 44,513   50,647   55,926   63,918   101,109

X(654) = isogonal conjugate of X(655)
X(654) = X(110)-Ceva conjugate of X(215)
X(654) = crosssum of X(I) and X(J) for these (I,J): (1,654), (517,650)
X(654) = crossdifference of every pair of points on line X(1)X(5)


X(655) = TRILINEAR POLE OF LINE X(1)X(5)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/[cos(A - B) - cos(C - A)]
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin A f(A,B,C)

X(655) lies on these lines: 59,523   80,516   100,522   514,651

X(655) = isogonal conjugate of X(654)


X(656) = CROSSDIFFERENCE OF X(1) AND X(19)

Trilinears        tan B - tan C : tan C - tan A : tan A - tan B
Barycentrics  sin A (tan B - tan C) : sin B (tan C - tan A) : sin C (tan A - tan B)

X(656) lies on these lines: 44,513   240,522   521,810   662,1101   667,832

X(656) = reflection of X(I) in X(J) for these (I,J): (1459,905)
X(656) = isogonal conjugate of X(162)
X(656) = isotomic conjugate of X(811)
X(656) = X(I)-Ceva conjugate of X(J) for these (I,J): (162,1), (163,38)
X(656) = X(125)-cross conjugate of X(201)
X(656) = crosspoint of X(I) and X(J) for these (I,J): (1,162), (521, 522)
X(656) = crosssum of X(I) and X(J) for these (I,J): (1,656), (31,661), (108,109), (513,1104), (663,1195)
X(656) = crossdifference of every pair of points on line X(1)X(19)


X(657) = CROSSDIFFERENCE OF X(1) AND X(7)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = (1 + cos A)(cos B - cos C)
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin A f(A,B,C)

X(657) lies on these lines: 9,522   44,513   59,101   663,853

X(657) = isogonal conjugate of X(658)
X(657) = X(101)-Ceva conjugate of X(55)
X(657) = crosspoint of X(55) and X(101)
X(657) = crosssum of X(I) and X(J) for these (I,J): (1,657), (7,514), (354,650), (614,649), (651,934), (905,1439)

X(657) = crossdifference of every pair of points on line X(1)X(7)


X(658) = TRILINEAR POLE OF LINE X(1)X(7)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/[(1 + cos A)(cos B - cos C)]
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin A f(A,B,C)

X(658) lies on these lines:
7,11   57,673   88,279   100,664   109,927   190,1020

X(658) = isogonal conjugate of X(657)
X(658) = isotomic conjugate of X(3239)
X(658) = X(514)-cross conjugate of X(7)


X(659) = CROSSDIFFERENCE OF X(1) AND X(39)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (a2 - bc)(b - c)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(659) lies on these lines:
1,891   23,385   44,513   100,190   105,884   291,875   292,665   514,667

X(659) = reflection of X(I) in X(J) for these (I,J): (876,665), (1491,650)
X(659) = isogonal conjugate of X(660)
X(659) = X(98)-Ceva conjugate of X(11)
X(659) = crosspoint of X(100) and X(105)
X(659) = crosssum of X(I) and X(J) for these (I,J): (1,659), (9,926), (141,918), (291,876), (292,875), (513,518)
X(659) = crossdifference of every pair of points on line X(1)X(39)


X(660) = TRILINEAR POLE OF LINE X(1)X(39)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[(a2 - bc)(b - c)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(660) lies on these lines:
44,292   88,291   100,649   190,513   239,335   320,334   512,1016   662,765

X(660) = isogonal conjugate of X(659)
X(660) = X(511)-cross conjugate of X(59)


X(661) = CROSSDIFFERENCE OF X(1) AND X(21)

Trilinears        cot B - cot C : cot C - cot A : cot A - cot B
                        = b2 - c2 : c2 - a2 : a2 - b2                         = SB - SC : SC - SA : SA - SB
Barycentrics  sin A (cot B - cot C) : sin B (cot C - cot A) : sin C (cot A - cot B)

X(661) is the perspector of triangle ABC and the tangential triangle of the conic that passes through the points A, B, C, X(1), and X(10). (Randy Hutson, 9/23/2011)

X(661) lies on these lines: 44,513   514,693   663,810

X(661) = reflection of X(649) in X(650)
X(661) = isogonal conjugate of X(662)
X(661) = isotomic conjugate of X(799)
X(661) = X(I)-Ceva conjugate of X(J) for these (I,J): (2,244), (162,31)
X(661) = crosspoint of X(I) and X(J) for these (I,J): (92,162), (513, 514)

X(661) = crosssum of X(I) and X(J) for these (I,J): (1,661), (21,1021), (48,656), (81,1019), (100,101), (513,1100), (649,1193), (667,1197), (820,822)

X(661) = crossdifference of every pair of points on line X(1)X(21)


X(662) = TRILINEAR POLE OF LINE X(1)X(21)

Trilinears        1/(cot B - cot C) : 1/(cot C - cot A) : 1/(cot A - cot B)
                        = 1/(b2 - c2) : 1/(c2 - a2) : 1/(a2 - b2)
Barycentrics  (sin A)/(cot B - cot C) : (sin B)/(cot C - cot A) : (sin C)/(cot A - cot B)

X(662) lies on these lines:
1,897   3,1098   6,757   27,913   48,75   60,404   81,88   86,142   99,101   100,110   109,931   214,759   243,425   261,572   326,610   333,909   648,653   656,1101   660,765   689,787   775,820   811,823   827,831

X(662) = isogonal conjugate of X(661)
X(662) = cevapoint of X(100) and X(101)
X(662) = X(I)-cross conjugate of X(J) for these (I,J): (100,99), (101,110), (163,162)
X(662) = crosssum of X(798) and X(810)


X(663) = CROSSDIFFERENCE OF X(2) AND X(7)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a(b - c)(b + c - a)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(663) lies on these lines:
1,514   41,884   101,919   106,840   187,237   513,855   650,861   657,853   661,810

X(663) = reflection of X(649) in X(667)
X(663) = isogonal conjugate of X(664)
X(663) = X(I)-Ceva conjugate of X(J) for these (I,J): (101,41), (109,6)
X(663) = crosspoint of X(I) and X(J) for these (I,J): (1,101), (6, 109)
X(663) = crosssum of X(I) and X(J) for these (I,J): (1,514), (2,522), (100,651), (521,1214), (693,1441)
X(663) = crossdifference of every pair of points on line X(2)X(7)


X(664) = TRILINEAR POLE OF LINE X(2)X(7)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a(b - c)(b + c - a)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(664) lies on these lines:
1,85   7,528   8,348   69,347   73,290   75,77   99,109   100,658   101,514   145,279   150,952   175,490   176,489   190,644   223,312   226,671   239,241   307,319   322,326   648,653   668,1026   1018,1025

X(664) = reflection of X(1121) in X(2)
X(664) = isogonal conjugate of X(663)
X(664) = isotomic conjugate of X(522)
X(664) = X(I)-cross conjugate of X(J) for these (I,J): (100,190), (514,85), (521, 333), (522,2)
X(664) = crosssum of X(512) and X(810)


X(665) = CROSSDIFFERENCE OF X(2) AND X(11)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a[(a - b)2(a + b - c) - (c - a)2(c + a - b)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(665) lies on these lines:
37,900   101,109   187,237   241,514   244,866   292,659   743,761

X(665) = midpoint of X(I) and X(J) for these (I,J): (649,665), (659,876)
X(665) = isogonal conjugate of X(666)
X(665) = crosssum of X(I) and X(J) for these (I,J): (2,918), (6,659), (294,885), (518,650)
X(665) = crossdifference of every pair of points on line X(2)X(11)


X(666) = TRILINEAR POLE OF LINE X(2)X(11)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc/[(a - b)2(a + b - c) - (c - a)2(c + a - b)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(666) lies on these lines:
99,919   101,514   105,898   190,522   239,294   527,673   644,668   645,670   1026,1027

X(666) = isogonal conjugate of X(665)
X(666) = isotomic conjugate of X(918)


X(667) = CROSSDIFFERENCE OF X(2) AND X(37)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a2(b - c)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(667) = radical center of the circumcircle, Brocard circle, and the circle with (diameter = segment X(1)X(3)) (Wilson Stothers, 3/31/2003)

X(667) lies on these lines:
3,1083   36,238   56,764   100,898   101,813   187,237   213,875   514,659   656,832   668,932   692,1110   788,798

X(667) = midpoint of X(649) and X(663)
X(667) = isogonal conjugate of X(668)
X(667) = inverse-in-circumcircle of X(1083)
X(667) = X(I)-Ceva conjugate of X(J) for these (I,J): (100,6), (101,213)
X(667) = crosspoint of X(I) and X(J) for these (I,J): (6,100), (58, 101)
X(667) = crosssum of X(I) and X(J) for these (I,J): (2,513), (10,514), (75,693), (100,1332), (120,918), (523,1211), (850,1234)

X(667) = crossdifference of every pair of points on line X(2)X(37)


X(668) = TRILINEAR POLE OF LINE X(2)X(37)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a2(b - c)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(668) lies on these lines:
2,1015   8,76   10,274   69,150   72,290   75,537   80,313   99,100   101,789   110,839   190,646   304,341   321,671   350,519   513,889   644,666   645,648   664,1026   667,932

X(668) = reflection of X(291) in X(10)
X(668) = isogonal conjugate of X(667)
X(668) = isotomic conjugate of X(513)
X(668) = anticomplement of X(1015)
X(668) = X(I)-cross conjugate of X(J) for these (I,J): (513,2), (514, 274)
X(668) = crosssum of X(669) and X(798)


X(669) = CROSSDIFFERENCE OF X(2) AND X(39)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a3(b2 - c2)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(669) lies on these lines:
23,385   25,878   31,875   99,886   110,805   187,237   684,924   688,864   804,850

X(669) = isogonal conjugate of X(670)
X(669) = X(99)-Ceva conjugate of X(6)
X(669) = crosspoint of X(I) and X(J) for these (I,J): (6,99), (110, 251)
X(669) = crosssum of X(I) and X(J) for these (I,J): (2,512), (76,850), (126,690), (141,523), (525,1368)
X(669) = crossdifference of every pair of points on line X(2)X(39)


X(670) = TRILINEAR POLE OF LINE X(2)X(39)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a3(b2 - c2)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(670) lies on these lines:
2,1084   69,290   76,338   99,804   110,689   141,308   190,799   310,903   512,886   645,666   850,892

X(670) = reflection of X(694) in X(141)
X(670) = isogonal conjugate of X(669)
X(670) = isotomic conjugate of X(512)
X(670) = anticomplement of X(1084)
X(670) = X(I)-cross conjugate of X(J) for these (I,J): (512,2), (523,308)
X(670) = crossdifference of every pair of points on line X(887)X(1084)


X(671) = TRILINEAR POLE OF LINE X(2)X(523)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a(2a2 - b2 - c2)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

If you have The Geometer's Sketchpad, you can view X(671).

X(671) lies on these lines:
2,99   4,542   6,598   10,190   13,531   14,530   30,98   76,338   83,597   226,664   262,381   316,524   321,668   485,489   486,490

X(671) = midpoint of X(2) and X(148)
X(671) = reflection of X(I) in X(J) for these (I,J): (2,115), (99,2)
X(671) = isogonal conjugate of X(187)
X(671) = isotomic conjugate of X(524)
X(671) = cevapoint of X(6) and X(23)
X(671) = X(316)-cross conjugate of X(83)


X(672) = CROSSDIFFERENCE OF X(1) AND X(514)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a[b2 + c2 - a(b + c)]
Trilinears        a(as - Sω) : b(bs - Sω) : c(cs - Sω)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(672) lies on these lines:
1,1002   2,7   3,41   6,31   36,101   37,38   39,213   43,165   44,513  46,169   56,220   72,1009   103,919   105,238   190,350   219,604   519,1018

X(672) = isogonal conjugate of X(673) X(672) = X(I)-Ceva conjugate of X(J) for these (I,J): (103,55), (291,42)
X(672) = crosspoint of X(I) and X(J) for these (I,J): (6,292), (241,518)
X(672) = crosssum of X(I) and X(J) for these (I,J): (1,672), (2,239), (105,294)
X(672) = crossdifference of every pair of points on line X(1)X(514)
X(672) = X(I)-Hirst inverse of X(J) for these (I,J): (6,55), (1362,1458)


X(673) = TRILINEAR POLE OF LINE X(1)X(514)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc/[b2 + c2 - a(b + c)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(673) lies on these lines:
2,11   6,7   9,75   19,273   27,162   57,658   86,142   238,516   239,335   310,333   527,666   675,919   812,1024   885,900

X(673) = reflection of X(I) in X(J) for these (I,J): (7,1086), (190,9)
X(673) = isogonal conjugate of X(672)
X(673) = cevapoint of X(I) and X(J) for these (I,J): (2,239), (105,294)
X(673) = X(I)-cross conjugate of X(J) for these (I,J): (238,86), (516,7)
X(673) = crossdifference of every pair of points on line X(665)X(926)


X(674) = CROSSDIFFERENCE OF X(6) AND X(514)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a[b3 + c3 - a(b2 + c2)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(674) lies on the line at infinity.

X(674) lies on these (parallel) lines: 6,31   30,511   51,210

X(674) = isogonal conjugate of X(675)
X(674) = crossdifference of every pair of points on line X(6)X(514)


X(675) = TRILINEAR POLE OF LINE X(6)X(514)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc/[b3 + c3 - a(b2 + c2)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(675) lies on the circumcircle.

X(675) lies on these lines:
2,101   7,109   27,112   75,100   86,110   99,310   108,273   335,813   673,919   789,871   901,903   934,1088

X(675) = isogonal conjugate of X(674)
X(675) = isotomic conjugate of X(3006)


X(676) = CROSSDIFFERENCE OF X(3) AND X(101)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc(b - c)[b3 + c3 - 2a3 + (b + c)(a2 - bc)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(676) = radical center of the circumcircle, nine-point circle, and incircle (Wilson Stothers, 3/31/2003)

X(676) lies on these lines: 11,244   105,659   230,231   928,942

X(676) = isogonal conjugate of X(677)
X(676) = crosspoint of X(105) and X(108)
X(676) = crosssum of X(I) and X(J) for these (I,J): (6,926), (518,521)
X(676) = crossdifference of every pair of points on line X(3)X(101)


X(677) = TRILINEAR POLE OF LINE X(3)X(101)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a/{(b - c)[b3 + c3 - 2a3 + (b + c)(a2 - bc)]}
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(677) lies on these lines: 59,1813   103,901   518,1814   521,651   765,1332   883,2398   1252,1331   1815,2340   2323,2338

X(677) = isogonal conjugate of X(676)


X(678) = CROSSPOINT OF X(1) AND X(44)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = (b + c - 2a)2
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(678) lies on these lines: 1,88   44,902   45,55

X(678) = isogonal conjugate of X(679)
X(678) = X(1)-Ceva conjugate of X(44)
X(678) = crosspoint of X(1) and X(44)
X(678) = crosssum of X(I) and X(J) for these (I,J): (1,88), (244,1022)
X(678) = crossdifference of every pair of points on line X(88)X(1022)


X(679) = ISOGONAL CONJUGATE OF X(678)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/(b + c - 2a)2
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(679) lies on these lines: 44,88   320,519

X(679) = isogonal conjugate of X(678)
X(679) = cevapoint of X(1) and X(88)
X(679) = X(1)-cross conjugate of X(88)


X(680) = CROSSDIFFERENCE OF X(6) AND X(158)

Trilinears        f(A,B,C): f(B,C,A) : f(C,A,B), where f(A,B,C) = cos2A (sin B cos2B - sin C cos2C)
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin A f(A,B,C)

As the isogonal conjugate of a point on the circumcircle, X(680) lies on the line at infinity.

X(680) lies on this line: 30,511  

X(680) = isogonal conjugate of X(681)
X(680) = crossdifference of every pair of points on line X(6)X(158)


X(681) = TRILINEAR POLE OF LINE X(6)X(158)

Trilinears        f(A,B,C): f(B,C,A) : f(C,A,B), where f(A,B,C) = (sec2A)/(sin B cos2B - sin C cos2C)
Barycentrics  (sin A)f(A,B,C): (sin B)f(B,C,A) : (sin C)f(C,A,B)

X(681) lies on the circumcircle.

X(681) lies on this line: 110,823

X(681) = isogonal conjugate of X(680)


X(682) = POINT ARNEB

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sec B csc3C + sec C csc3B
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin A f(A,B,C)

X(682) lies on these lines: 3,69   154,237   248,695

X(682) = isogonal conjugate of X(683)
X(682) = crosspoint of X(3) and X(32)
X(682) = crosssum of X(4) and X(76)


X(683) = ISOGONAL CONJUGATE OF X(682)

Trilinears        f(A,B,C): f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/[sec B csc3C + sec C csc3B]
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin A f(A,B,C)

X(683) lies on this line: 25,305

X(683) = isogonal conjugate of X(682)
X(683) = cevapoint of X(4) and X(76)


X(684) = CROSSDIFFERENCE OF X(4) AND X(32)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sec B sin3 C - sec C sin3 B
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin A f(A,B,C)

X(684) lies on these lines: 110,351   114,132   122,125   147,804   325,523   520,647   669,924

X(684) = isogonal conjugate of X(685)
X(684) = crosspoint of X(99) and X(287)
X(684) = crosssum of X(I) and X(J) for these (I,J): (98,879), (232,512)
X(684) = crossdifference of every pair of points on line X(4)X(32)


X(685) = TRILINEAR POLE OF LINE X(4)X(98)

Trilinears        f(A,B,C): f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/(sec B sin3 C - sec C sin3 B)
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin A f(A,B,C)

X(685) lies on these lines: 98,468   110,850   250,523   287,297

X(685) = isogonal conjugate of X(684)


X(686) = CROSSDIFFERENCE OF X(4) AND X(110)

Trilinears        f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = sec B csc(A - B) + sec C csc(A - C)
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin A f(A,B,C)

X(686) lies on these lines: 115,125   184,351   520,647

X(686) = isogonal conjugate of X(687)
X(686) = crossdifference of every pair of points on line X(4)X(110)


X(687) = TRILINEAR POLE OF LINE X(4)X(110)

Trilinears        f(A,B,C): f(B,C,A) : f(C,A,B), where f(A,B,C) = 1/[sec B csc(A - B) + sec C csc(A - C)]
Barycentrics  g(A,B,C) : g(B,C,A) : g(C,A,B), where g(A,B,C) = sin A f(A,B,C)

X(687) lies on these lines: 107,250   249,648

X(687) = isogonal conjugate of X(686)


X(688) = CROSSDIFFERENCE OF X(6) AND X(76)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a3(b4 - c4)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(688) lies on the line at infinity.

X(688) lies on these (parallel) lines: 6,882   30,511   669,864   798,872

X(688) = isogonal conjugate of X(689)
X(688) = crosssum of X(99) and X(670)
X(688) = crossdifference of every pair of points on line X(6)X(76)


X(689) = TRILINEAR POLE OF LINE X(6)X(76)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a3(b4 - c4)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(689) = isotomic conjugate of X(3005)

X(689) lies on the circumcircle and these lines:
1,719   2,733   6,703   75,745   76,755   82,715   83,729   110,670   111,308   251,699   662,787   741,873   799,813

X(689) = isogonal conjugate of X(688)


X(690) = CROSSDIFFERENCE OF LINE X(6) AND X(110)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = bc(b2 - c2)(2a2 - b2 - c2)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(690) lies on the line at infinity.

X(690) lies on these (parallel) lines:
30,511   74,98   99,110   113,114   115,125   146,147

X(690) = orthopoint of X(542)
X(690) = isogonal conjugate of X(691)
X(690) = isotomic conjugate of X(892)
X(690) = X(67)-Ceva conjugate of X(125)
X(690) = crosssum of X(I) and X(J) for these (I,J): (6,351), (187,512), (523,858)
X(690) = crossdifference of every pair of points on line X(6)X(110)


X(691) = TRILINEAR POLE OF LINE X(6)X(110)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a/[(b2 - c2)(2a2 - b2 - c2)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(691) is the antipode of X(842) on the circumcircle.

Let LA be the line of reflection of the line X(6)X(13) in line BC, and define LB and LC cyclically. Let A' = LB∩LC, and define B' and C' cyclically. Then the lines AA', BB', CC' concur in X(691). (Randy Hutson, 9/23/2011)

X(691) lies on these lines:
3,842   6,843   23,111   30,98   74,511   99,523   110,249   112,250   316,858   376,477   741,923   759,897   805,882

X(691) = reflection of X(I) in X(J) for these (I,J): (23,187), (316,858), (842,3)
X(691) = isogonal conjugate of X(690)
X(691) = cevapoint of X(6) and X(351)
X(691) = X(I)-cross conjugate of X(J) for these (I,J): (23,250), (187,249), (351,6)


X(692) = X(110)-CEVA CONJUGATE OF X(101)

Trilinears        a2/(b - c) : b2/(c - a) : c2/(a - b)
Barycentrics  a3/(b - c) : b3/(c - a) : c3/(a - b)

X(692) lies on these lines:
25,913   48,911   55,184   59,513   99,785   100,110   101,926   154,197   163,906   182,1001   206,219   213,923   667,1110   813,825

X(692) = isogonal conjugate of X(693)
X(692) = X(I)-Ceva conjugate of X(J) for these (I,J): (59,6), (110,101)
X(692) = cevapoint of X(I) and X(J) for these (I,J): (101,109), (110,163)
X(692) = crosssum of X(I) and X(J) for these (I,J): (2,149), (513,905), (514,522), (764,1086)
X(692) = crossdifference of every pair of points on line X(918)X(1086)


X(693) = ISOTOMIC CONJUGATE OF X(100)

Trilinears        (b - c)/a2 : (c - a)/b2 : (a - b)/c2
Barycentrics  (b - c)/a : (c - a)/b : (a - b)/c

X(693) lies on these lines:
2,650   76,764   100,927   320,350   321,824   325,523   514,661   649,812

X(693) = isogonal conjugate of X(692)
X(693) = isotomic conjugate of X(100)
X(693) = anticomplement of X(650)
X(693) = cevapoint of X(2) and X(149)
X(693) = X(I)-cross conjugate of X(J) for these (I,J): (11,2), (523,514)
X(693) = crosssum of X(I) and X(J) for these (I,J): (31,667), (42,663), (649,1475)
X(693) = crossdifference of every pair of points on line X(31)X(32)


X(694) = ISOGONAL CONJUGATE OF X(385)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a/(a4 - b2c2)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(694) lies on these lines:
6,1084   37,256   42,893   110,251   111,805   141,308   172,904   257,335   351,881   384,695   882,888

X(694) = reflection of X(I) in X(J) for these (I,J): (6,1084), (670,141)
X(694) = isogonal conjugate of X(385)
X(694) = cevapoint of X(384) and X(385)
X(694) = X(I)-cross conjugate of X(J) for these (I,J): (446,232), (511,6)


X(695) = ISOGONAL CONJUGATE OF X(384)

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a/(a4 + b2c2)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(695) lies on these lines: 69,194   99,711   248,682   384,694

X(695) = isogonal conjugate of X(384)


X(696) = EVEN (- 4, - 3) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -5(b -3 + c -3) - a -4(b -4 + c -4)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(696) lies on the line at infinity. The first trilinear coordinate has the form

am-1(bn + cn) - an-1(bm + cm).

If m and n are distinct integers, this form fits the definition of even polynomial center as in Clark Kimberling, "Functional equations associated with triangle geometry," Aequationes Mathematicae 45 (1993) 127-152. This form, perhaps appearing initially here (July 7, 2001) defines a triangle center for arbitrary distinct real numbers m and n. Selected even infinity and circumcircle points begin at X(696); odd ones begin at X(768).

Certain points of this type occur prior to this section. They are as follows:

     X(538) = even (- 2, 0) infinity point
     X(536) = even (- 1, 0) infinity point
     X(519) = even (0, 1) infinity point
     X(106) = even (0, 1) circumcircle point
     X(524) = even (0, 2) infinity point
     X(111) = even (0, 2) circumcircle point
     X(518) = even (1, 2) infinity point
     X(105) = even (1, 2) circumcircle point
     X(674) = even (2, 3) infinity point
     X(675) = even (2, 3) circumcircle point
     X(511) = even (2, 4) infinity point
     X(98) = even (2, 4) circumcircle point

X(696) lies on these lines: 30,511   313,561

X(696) = isogonal conjugate of X(697)


X(697) = EVEN (- 4, - 3) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -5(b -3 + c -3) - a -4(b -4 + c -4)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(697) lies on the circumcircle. This is one of several points of the form given by first trilinear

1/[am-1(bn + cn) - an-1(bm + cm)],

hence the name "(m, n)-circumcircle point".

X(697) lies on this line: 100,560

X(697) = isogonal conjugate of X(696)


X(698) = EVEN (- 4, - 2) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -5(b -2 + c -2) - a -3(b -4 + c -4)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(698) lies on the line at infinity.

X(698) lies on these (parallel) lines: 6,194  30,511   75,257  76,141

X(698) = isogonal conjugate of X(699)
X(698) = isotomic conjugate of X(3225)


X(699) = EVEN (- 4, - 2) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -5(b -2 + c -2) - a -3(b -4 + c -4)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(699) lies on the circumcircle.

X(699) lies on these lines: 32,99   172,932   251,689

X(699) = isogonal conjugate of X(698)
X(699) = X(385)-cross conjugate of X(251)


X(700) = EVEN (- 4, - 1) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -5(b -1 + c -1) - a -2(b -4 + c -4)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(700) lies on the line at infinity.

X(700) lies on this line: 30,511   75,871

X(700) = isogonal conjugate of X(701)


X(701) = EVEN (- 4, - 1) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -5(b -1 + c -1) - a -2(b -4 + c -4)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(701) lies on the circumcircle.

X(701) lies on this line: 31,789

X(701) = isogonal conjugate of X(700)


X(702) = EVEN (- 4, 0) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -5(b0 + c0) - a -1(b -4 + c -4)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(702) lies on the line at infinity.

X(702) lies on these lines: 2,308   30,511

X(702) = isogonal conjugate of X(703)


X(703) = EVEN (- 4, 0) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -5(b0 + c0) - a -1(b -4 + c -4)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(703) lies on the circumcircle.

X(703) lies on this line: 6,689

X(703) = isogonal conjugate of X(702)


X(704) = EVEN (- 4, 1) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -5(b1 + c1) - a0(b -4 + c -4)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(704) lies on the line at infinity.

X(704) lies on this line: 30,511

X(704) = isogonal conjugate of X(705)


X(705) = EVEN (- 4, 1) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -5(b1 + c1) - a0(b -4 + c -4)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(705) lies on the circumcircle.

X(705) = isogonal conjugate of X(704)


X(706) = EVEN (- 4, 2) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -5(b2 + c2) - a1(b -4 + c -4)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(706) lies on the line at infinity.

X(706) lies on this line: 30,511

X(706) = isogonal conjugate of X(707)


X(707) = EVEN (- 4, 2) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -5(b2 + c2) - a1(b -4 + c -4)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(707) lies on the circumcircle.

X(707) = isogonal conjugate of X(706)


X(708) = EVEN (- 4, 3) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -5(b3 + c3) - a2(b -4 + c -4)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(708) lies on the line at infinity.

X(708) lies on this line: 30,511

X(708) = isogonal conjugate of X(709)


X(709) = EVEN (- 4, 3) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -5(b3 + c3) - a2(b -4 + c -4)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(709) lies on the circumcircle.

X(709) = isogonal conjugate of X(708)


X(710) = EVEN (- 4, 4) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -5(b4 + c4) - a3(b -4 + c -4)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(710) lies on the line at infinity.

X(710) lies on this line: 30,511

X(710) = isogonal conjugate of X(711)


X(711) = EVEN (- 4, 4) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -5(b4 + c4) - a3(b -4 + c -4)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(711) lies on the circumcircle.

X(711) lies on this line: 99,695

X(711) = isogonal conjugate of X(710)


X(712) = EVEN (- 3, - 2) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -4(b -2 + c -2) - a -3(b -3 + c -3)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(712) lies on the line at infinity.

X(712) lies on these lines: 30,511   76,321

X(712) = isogonal conjugate of X(713)


X(713) = EVEN (- 3, - 2) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -4(b -2 + c -2) - a -3(b -3 + c -3)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(713) lies on the circumcircle.

X(713) lies on these lines: 32,100   101,560

X(713) = isogonal conjugate of X(712)


X(714) = EVEN (- 3, - 1) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -4(b -1 + c -1) - a -2(b -3 + c -3)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(714) lies on the line at infinity.

X(714) lies on these lines: 30,511   38,75

X(714) = isogonal conjugate of X(715)


X(715) = EVEN (- 3, - 1) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -4(b -1 + c -1) - a -2(b -3 + c -3)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(715) lies on the circumcircle.

X(715) lies on these lines: 31,99   81,932   82,689   110,560

X(715) = isogonal conjugate of X(714)


X(716) = EVEN (- 3, 0) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -4(b0 + c0) - a -1(b -3 + c -3)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(716) lies on the line at infinity.

X(716) lies on these lines: 2,561   30,511

X(716) = isogonal conjugate of X(717)


X(717) = EVEN (- 3, 0) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -4(b0 + c0) - a -1(b -3 + c -3)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(717) lies on the circumcircle.

X(717) lies on these lines: 6,789   560,825

X(717) = isogonal conjugate of X(716)


X(718) = EVEN (- 3, 1) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -4(b1 + c1) - a0(b -3 + c -3)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(718) lies on the line at infinity.

X(718) lies on these lines: 1,561   30,511

X(718) = isogonal conjugate of X(719)


X(719) = EVEN (- 3, 1) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -4(b1 + c1) - a0(b -3 + c -3)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(719) lies on the circumcircle.

X(719) lies on these lines: 1,689   560,827

X(719) = isogonal conjugate of X(718)


X(720) = EVEN (- 3, 2) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -4(b2 + c2) - a1(b -3 + c -3)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(720) lies on the line at infinity.

X(720) lies on these lines: 6,561   30,511

X(720) = isogonal conjugate of X(721)


X(721) = EVEN (- 3, 0) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -4(b2 + c2) - a1(b -3 + c -3)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(721) lies on the circumcircle.

X(721) = isogonal conjugate of X(720)


X(722) = EVEN (- 3, 3) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -4(b3 + c3) - a2(b -3 + c -3)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(722) lies on the line at infinity.

X(722) lies on this line: 30,511

X(722) = isogonal conjugate of X(723)


X(723) = EVEN (- 3, 3) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -4(b3 + c3) - a2(b -3 + c -3)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(723) lies on the circumcircle.

X(723) = isogonal conjugate of X(722)


X(724) = EVEN (- 3, 4) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -4(b4 + c4) - a3(b -3 + c -3)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(724) lies on the line at infinity.

X(724) lies on this line: 30,511

X(724) = isogonal conjugate of X(725)


X(725) = EVEN (- 3, 4) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -4(b4 + c4) - a3(b -3 + c -3)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(725) lies on the circumcircle.

X(725) = isogonal conjugate of X(724)


X(726) = EVEN (- 2, -1) INFINITY POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = a -3(b -1 + c -1) - a -2(b -2 + c -2)
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

As the isogonal conjugate of a point on the circumcircle, X(726) lies on the line at infinity.

X(726) lies on these (parallel) lines: 1,87   10,75   30,511  37,39   38,321   190,238   291,350   312,982

X(726) = isogonal conjugate of X(727)
X(726) = isotomic conjugate of X(3226)
X(726) = X(291)-Ceva conjugate of X(10)
X(726) = crosspoint of X(75) and X(335)


X(727) = EVEN (- 2, -1) CIRCUMCIRCLE POINT

Trilinears        f(a,b,c) : f(b,c,a) : f(c,a,b), where f(a,b,c) = 1/[a -3(b -1 + c -1) - a -2(b -2 + c -2)]
Barycentrics  g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = af(a,b,c)

X(727) lies on the circumcircle.

X(727) lies on these lines: 1,932   31,43   32,101   58,99   789,985   934,1106

X(727) = isogonal conjugate of X(726)
X(727) = X(238)-cross conjugate of X(58)


X(728) = INTERSECTION OF LINES X(8)X(9) AND X(57)X(345)

Trilinears        f(a,b,c) : f(b,c,a) :