Side-Angle-Side (SAS) Congruence Dynamic Demonstration

This GeoGebra example dynamically demonstrates the Side-Angle-Side (SAS) criterion for triangle congruence. It visually shows that when two sides and the included angle are fixed, the third side and the remaining two angles are uniquely determined, thereby illustrating that SAS is a sufficient condition for triangle congruence. Core mathematical concepts include triangle congruence, the SAS postulate, geometric construction, and dynamic geometry. Construction highlights: the Segment command is used to create sides AB and AC, the Angle command marks the included angle α, and the Point command defines vertex C; additional segments and angle objects (such as f, g, h, D, E, i, F, j, k, β, γ, δ, ε, ζ) are constructed to show relationships among elements. Suitable for middle school geometry instruction, helping students understand congruence theorems, and useful for classroom demonstrations or self-directed exploration.