The two column proof has shown that AB ≅ CD because of CPCTC
How to use the two column proof?
The two column proof to show that AB ≅ CD is:
Statement 1: AB ║ CD, AD ║ BC
Reason 1: Given
Statement 2: ∠ABD ≅ ∠CDB
Reason 2: Alternate angles
Statement 3: ∠ADB ≅ ∠CBD
Reason 3: Alternate angles
Statement 4: BD ≅ BD
Reason 4: Reflexive property of congruency
Statement 5: ΔABD ≅ ΔCDB
Reason 5: SAS Congruency Postulate
Statement 6: AB ≅ CD
Reason 6: CPCTC