Given:
A figure of two congruent triangles.
To find:
The triangle congruence postulate by which the given triangles are congruent.
Solution:
First label the vertices as shown below.
In triangle ABC and triangle CDA,
(Given)
(Given)
(Common side)
The corresponding two sides and their included angle are congruent in both triangles. So, triangles are congruent by SAS congruence postulate.
[SAS congruence postulate]
Therefore, the correct option is B.
