Triangle Reflection Demonstration

This example demonstrates the reflection (mirror) transformation of a triangle across a line, showing the original triangle and its reflected image to visualize positional and orientational changes. The core mathematical concept is reflection (axial symmetry) in plane geometry, involving properties such as the perpendicular bisector relationship between corresponding points and the axis. Construction highlights: using GeoGebra's Polygon command to create triangle poly1 (vertices A, B, C), Line command to define the reflection axis c, then applying reflection to generate corresponding points D, E and the reflected triangle (object d), while retaining original sides a, b. Suitable for middle school geometry or introductory high school analytic geometry, helping students understand the geometric meaning and construction of axial symmetry.