Help with this problem

Question

In triangle abc side ab is congruent to side cb and angle a is congruent to angle b what must be true about triangle abc

Answer 1

The angle opposite side ab is ∠c and the angle opposite side bc is ∠a.

Since ab ≅ bc, ∠c ≅ ∠a. But, by assumption, ∠a ≅ ∠b.

So, all 3 interior angles of the triangle are congruent.

Therefore, the triangle is equilateral.