Respuesta :
Answer: Step 6 : CPCTC
Step-by-step explanation:
CPCTC states that corresponding part of the congruent triangles are congruent.
Here, Given: abcd is a quadrilateral,
In which ad ≅ bc and ad║bc
Prove : abcd is a parallelogram.
        Statement                          Reason
1. ad ≅ bc; ad║bc                    1. Given
2.∠cad and ∠acb are alternative angles  2. Definition of alternative angles
3. ∠cad≅∠acb                       3. alternative angles are congruent
4. ac ≅ ac                           4. Reflexive property
5.△cad ≅ △acb                      5. SAS congruence postulate
6. .ab ≅ cd                          6. CPCTC
7. abcd is a parallelogram             7. Parallelogram side theorem
