Question

Given: AD ≅ BC and AD ∥ BC Prove: ABCD is a parallelogram. Statements Reasons 1. AD ≅ BC; AD ∥ BC 1. given 2. ∠CAD and ∠ACB are alternate interior ∠s 2. definition of alternate interior angles 3. ∠CAD ≅ ∠ACB 3. alternate interior angles are congruent 4. AC ≅ AC 4. reflexive property 5. △CAD ≅ △ACB 5. SAS congruency theorem 6. AB ≅ CD 6. ? 7. ABCD is a parallelogram 7. parallelogram side theorem What is the missing reason in step 6? SSS congruency theorem CPCTC definition of a parallelogram opposite sides in a parallelogram are congruent

Answer 1

The answer is CPCTC because we already proved it in the perious steps

Answer 2

Because in the previous step we proved that two triangles were congruent, the answer is CPCTC.