Triangle ABC has been dilated to form triangle A'B'C'. If sides AB and A'B' are proportional, what is the least amount of additional information needed to determine if the two triangles are similar?

Answer with step-by-step explanation:

When we are considering the similar triangles, we need the congruent angles and the proportional sides.

So we need to know of at least two angles that are congruent to their corresponding angles in order to prove the similarity of two triangles.

For example:

Angles B and B' are congruent, and angles C and C' are congruent.

So this is the least amount of additional information that we need to prove the similarity of two triangles.