∵AB=AC, point D.E is the bisector of BC, and AD=AE.

∴BD=EC

∴BD+DE=CE+DE means.

△ABE?△ACD

2

∫AB//DC, AD//BC

∴∠MPD=∠QNB,∠M=∠Q

MN = PQ

Mn+NP = PQ+NP means MP=NQ.

∴△MDP≌△QBN

∴DP=BN