Proof 1
Given: AB║CD , AD║CB
Prove: ΔABC ≅ΔCDA

Statement Reason
AB║CD , AD║CB Given
m∠BAC = m∠ACD Alternate Interior Angles
m∠ACB = m∠CAD Alternate Interior Angles
AC = AC Reflexive Property of Equality
ΔABC ≅ΔCDA ASA ≅