Thomsen's Figure

Thomsen's figure is illustrated by the following process. For any triangle , pick a point on opposite . From , draw a line segment parallel to intersecting at point , then from there a segment parallel to intersecting at . Continue through the figure. Thomsen's theorem states that the final segment from parallel to terminates at the original point .
Drag the triangle vertices , and to illustrate the diagram for different triangles. The slider moves between the vertices and .


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[1] Wikipedia. "Thomsen's Theorem." (Jan 26, 2022)
[2] "Thomsen's Theorem." Futility Closet. (Jan 26, 2022)
[3] E. W. Weisstein. "Thomsen's Figure." (Jan 26, 2022) Wolfram MathWorld—A Wolfram Web Resource.
[4] E. W. Weisstein. "Thomsen's Figure." (Jan 26, 2022) (same as [3], except MW description is wrong).
[5] Wikipedia. "Pappus's Hexagon Theorem." (Jan 26, 2022)
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