Alternate Exterior Angles of Parallel Lines – Dynamic GeoGebra Demo

① This GeoGebra example dynamically demonstrates that when two parallel lines are cut by a transversal, the alternate exterior angles (angles lying outside the parallel lines on opposite sides of the transversal) are equal. ② It covers core geometry concepts: parallel lines, transversals, alternate exterior angles, corresponding angles, and angle measurement, essential for middle school Euclidean geometry. ③ Construction: using GeoGebra commands such as Segment, Line, Point, Intersect, and Angle, the applet creates lines f, g, h, intersection points A–H, and labeled angles α, β, γ, δ. Users can drag the transversal or the parallel lines to observe that the alternate exterior angles remain congruent. ④ This resource is ideal for middle school teachers for classroom demonstration, for students to explore and conjecture, and for introductory geometry lessons to build visual intuition and deductive reasoning about parallel line angle relationships.