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