1. ABCD is a quadrilateral in which AD = BC and ∠DAB = ∠CBA. Prove that δABD ≌ ΔBAC.

Step-by-step explanation:
ABCD is a quadrilateral triangle,where AD=BC and <DAB =<CBA.
In ∆ABD and ∆BAC
•AD=BC. (given)
•<DAB=<CBA (given)
•AB=BA. (common side)
Therefore, ∆ABD ≌ ΔBAC. {SAS congruence rule}