Similar triangles have congruent corresponding angles and proportional corresponding sides. In this topic, you learned about three criteria that prove two triangles are similar. The SSS Similarity Theorem states that corresponding sides have the same ratio. Two triangles are similar by the SAS Similarity Theorem when two corresponding sides have the same ratio and the corresponding included angles are congruent. Lastly, two triangles are congruent by the AA Similarity Postulate when two corresponding angles are congruent.