Triangle Congruence Theorem: Identifying the Proof for ADE ≅ BCE

ΔEDC is an isosceles triangle.

DE = EC

$∢D=∢C$

$∢\text{EDC}=∢\text{ECD}$

$∢\text{ADE}=∢\text{BCE}$(A)

$∢E1=∢E2$(A)

Reasoning:

In an isosceles triangle there are 2 equal sides.

The base angles of an isosceles triangle are equal.

$∢D-∢\text{EDC}=∢C-∢ECD$

Therefore, the triangles are congruent according to the theorem S.A.S. theorem.