This page uses **JavaSketchpad**, a World-Wide-Web component of *The Geometer's Sketchpad.* Copyright © 1990-2001 by KCP Technologies, Inc. Licensed only for non-commercial use.

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InvertLine

Nine points on a line are inverted in the circle *(O,Z)* to form nine points on a circle.
The point *X* between *P* and *Q* determines the ratio |*QX*|/|*QP*|. This ratio is used to dilate the 9 points to a set of 9 intermediate points, which are linked by blue segments and reflected in segment *PQ*. When *X* is animated, the linkage moves so as to represent a "slow motion inversion" of the line into the circle (and of the circle into the line).

For more, see *GEOMETRY IN ACTION*, Chapter 3.