In Unit 3, we learned about similar triangles. We learned that similar triangles with a zoom factor of 1 are congruent triangles. In this unit, we will learn more about what makes one triangle congruent to another or not. Congruence of shapes is an important idea in mathematics and is used in many physical applications. We will remember the similarity conjectures and theorems: SSS~, AA~, and SAS~ and determine when we can use their congruence duals.