I know the relationships between corresponding sides and angles in similar triangles.
Today our focus is the definition of similarity, but using it backwards.
If we know triangles are similar, then we know corresponding angles are congruent and corresponding sides are in proportion.
For today, if we know that 2 triangles have congruent corresponding angles and their corresponding sides are in proportion, then we know they are similar...and...there is still a sequence of rigid motion and dilations that will take one shape onto another.