Respuesta :

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}