Euclid's Proof of the Pythagorean Theorem by Li

① This GeoGebra example dynamically demonstrates Euclid's classic proof of the Pythagorean theorem from the Elements, showing that the sum of the areas of the squares on the two legs of a right triangle equals the area of the square on the hypotenuse. ② Core mathematical concepts include right triangles, similar triangles, area conservation, rotation and translation transformations, and the geometric meaning of the Pythagorean theorem. ③ Construction highlights: using GeoGebra commands such as Intersect, Point, Line, Circle, Semicircle, Polygon, Angle, OrthogonalLine, Translate, Rotate, and Segment, the example constructs a right triangle and squares on each side, then uses auxiliary lines and rotated figures to partition the large square into parts equal in area to the two smaller squares, completing the proof. ④ Suitable for middle school to high school students learning geometric proofs, and useful for teachers demonstrating or students exploring multiple proofs of the Pythagorean theorem.