Gizmo of the Week: Proving Triangles Congruent

Establishing triangle congruence comes up again and again in geometric proofs. The Proving Triangles Congruent Gizmo allows students to explore the conditions that prove and do not prove triangle congruence. In the Gizmo, students specify conditions that are congruent in two triangles such as S, SA, SAS, etc. They can then manipulate the vertices of each triangle to see if they can create non-congruent triangles with the specified conditions. By allowing students to manipulate the triangles in this way, the Gizmo provides a way to simulate these conditions in a way that is not possible with pencil and paper.

The related Congruence in Right Triangles Gizmo allows students to explore the conditions that prove congruence for two right triangles.

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