# Geometry Unit 4: Triangle Congruence

The Geometry Unit 4: Triangle Congruence unit module contains five lessons—each with a video, teacher reference, practice packets, solutions, and corrective assignments. To begin, scholars review the types of triangles, then investigate the Isosceles Triangle Theorem and see how to apply it to solve problems. They also learn how to identify the corresponding parts of congruent triangles. The second of five lessons in the Geometry - Triangle Congruence unit focuses on the SSS and SAS triangle congruence criteria. Young mathematicians learn how to identify when SSS and SAS apply and how to use them in congruence proofs. Next, pupils learn about the AAS and ASA triangle congruence criteria and use these shortcuts to demonstrate triangle congruence in written proofs. The fourth of five lessons teaches learners how to use CPCTC to prove congruent parts. They also apply the HL Theorem to prove that two right triangles are congruent. To conclude the unit, class members review triangle classifications and how to use properties of triangles to set up and solve equations for missing values. They also review the triangle congruence criteria (SSS, SAS, ASA, AAS, HL) and apply them in triangle congruence proofs.