Angles in a Quadrilateral - Dynamic Sum Demonstration

This GeoGebra example dynamically demonstrates that the sum of the four interior angles of any quadrilateral is always 360°. It focuses on the core geometric concept of the quadrilateral angle-sum theorem, involving angle measurement, polygon interior angles, and visual verification. The construction uses the Polygon command to create quadrilateral poly1 with vertices A, B, C, D, and the Angle command to label the four interior angles α, β, γ, δ, with their values and total displayed in real time. Suitable for middle school geometry lessons, it allows students to drag vertices to observe how individual angles change while the sum remains constant, reinforcing the theorem and serving as a foundation for deriving the general polygon angle-sum formula.