4-4 Using Corresponding Parts of Congruent Triangles I can determine whether corresponding parts of triangles are congruent. I can write a two column proof for congruent triangles.

Corresponding Parts of Congruent Triangles are Congruent (CPCTC) If you know that two triangles are congruent, then every pair of their corresponding parts are congruent. Be careful: This may only be used to prove parts are congruent after you prove two triangles congruent!!

Practice Explain how you would use SSS, SAS, ASA, AAS, or HL with CPCTC to prove the following statements congruent:

Practice Explain how you would use SSS, SAS, ASA, AAS, or HL with CPCTC to prove the following statements congruent:

Practice Explain how you would use SSS, SAS, ASA, AAS, or HL with CPCTC to prove the following statements congruent:

Proofs with Congruent Triangles Reasons often used for these proofs: Reflexive Property Angle pairs formed by transversals (if given parallel lines) CPCTC Postulates for proving triangles congruent (SSS, SAS, HL, ASA, AAS) Definition of perpendicular Definition of vertical angles Definition of midpoint Definition of bisector All right angles are congruent to each other

Proofs with Congruent Triangles New reason: Third angles theorem – If two angles of one triangle are congruent to two angles of another triangle, then the third angle of the two triangles must be equal.