Thales' Theorem Geometric Construction Demo

This GeoGebra example demonstrates Thales' theorem (the intercept theorem): a line parallel to one side of a triangle divides the other two sides proportionally, producing similar triangles. Core concepts include proportional segments, similar triangles, parallel lines, and Euclidean geometric construction. The construction uses GeoGebra commands Line, Point, Intersect, and Segment, with objects such as points A, B, C, lines a, b, c, and segments d, e, f to build the proportional figure dynamically. Suitable for middle school geometry and high school similarity lessons, ideal for classroom demonstration and student exploration.