Sum of the Interior Angles in a Quadrilateral

①This GeoGebra example dynamically demonstrates that the sum of the four interior angles of any convex quadrilateral is always 360°. ②The core mathematical concept is the quadrilateral interior angle sum theorem, extending the general polygon angle sum formula (n-2)×180°, with emphasis on angle measurement and geometric reasoning. ③Construction highlights: using the Segment command to connect points A, B, C, D forming the quadrilateral, and the Point command to place auxiliary points E, F, G on sides or diagonals; angle labels and dynamic measurements update as vertices are dragged, showing individual angles and their total. ④Suitable for middle school geometry lessons or high school review, serving as an interactive exploration tool to help students verify the theorem and develop inductive thinking.