Geometry

Question Analysis:
This problem requires proving the congruence of two triangles within a quadrilateral using a diagonal as a common side.
The main focus is on determining which postulate applies.

Key Concept Explanation:
SSS Congruence Postulate states that if three sides of one triangle are congruent to three sides of another triangle, then the triangles are congruent.

Step-by-Step Solution:
Given conditions:
AB = CD (one pair of equal sides).
BC = DA (another pair of equal sides).
AC = AC (shared side, reflexive property).
Since all thr...