Question

What postulate or theorem is used in the picture below?

Answer 1

If we have that in two triangles we have that the corresponding sides and the included angle are congruent, then we can say that both triangles are congruent. This is called the SAS (side-angle-side) postulate.

Then, in summary, the method that proves that both triangles are congruent is SAS (Side-Angle-Side) postulate (second option).