Triangle Angle Sum Dynamic Demonstration

①This GeoGebra example dynamically demonstrates that the sum of the three interior angles of a triangle is always 180°, allowing users to drag vertices and observe that the total remains constant. ②The core mathematical concept is the triangle angle sum theorem, involving angle measurement, polygon interior angles, and geometric visualization. ③Construction details: The Polygon command creates triangle ABC, the Angle command marks interior angles α, β, γ, and a text object text1 displays the live sum; auxiliary objects t1, c, a, b, δ are included, possibly for auxiliary lines or angle annotations. ④It is suitable for middle school geometry lessons or upper elementary math enrichment, useful for classroom demonstrations, student self-exploration, or as dynamic courseware to reinforce the universality of the triangle angle sum theorem.