Two polygons are similar if their corresponding angles are congruent and their corresponding sides are proportional. If the corresponding angles of two polygons are congruent, the polygons must be similar. However, if the corresponding sides are proportional, the polygons do not necessarily have to be similar. While similar polygons have proportional sides and congruent angles, congruent polygons are always similar but not vice versa. All regular pentagons are similar since their corresponding angles and sides will always be congruent and proportional respectively.

1. Ratio, Proportion, and Similarity 7-3 Similar Polygons