Demonstrating Congruence Using a Line of Symmetry

This GeoGebra example demonstrates how to use a line of symmetry (reflection) to prove that two geometric figures are congruent. The core mathematical concepts involved include congruence, symmetry, reflection transformation, quadrilaterals, polygons, and angle relationships. The construction uses GeoGebra commands such as Intersect, Polygon, Segment, Point, and Angle, together with objects including points A–F, segments a–g, polygon poly1, and reflected objects a_1, b_1, c_1, e_1, with text labels text1–text9 providing explanatory annotations. It is suitable for middle school geometry instruction, especially for classroom demonstrations or student inquiry activities on axial symmetry and congruence criteria.