Reflection of Overlapping Triangles

This GeoGebra example demonstrates the reflection of two overlapping triangles across a line, producing a mirrored image that reveals symmetry and congruence. The core mathematical concepts include axial symmetry, reflection transformation, congruent figures, and the correspondence of special points such as vertices and intersection points. The construction uses the Polygon command to create the original triangle poly1, the Line command to define the mirror axis, and the Mirror command to reflect the polygon and its vertices, generating the reflected polygon poly1' and corresponding points A', B', C', etc. Auxiliary lines g, h, and i are included to highlight the symmetry relationships. This resource is suitable for middle school geometry lessons, helping students understand the properties of reflection, verify that size and shape are preserved, and explore how overlapping regions change under transformation.