Advertising dichotomy ∠CAE
∴∠CAD=∠EAD
AE = AC，AP=AP
∴△AEP≌△ACP
∴PE=PC
∫in△BPE:p b+ PC > Be，Be = AB+AE = AB+AC。
∴PB+PC>AB+AC
2. Proof: Take point E of AC side to make AE = AB, and then connect PE.
Advertising dichotomy ∠CAE
∴∠CAD=∠BAD
AE = AB，AP=AP
∴△AEP≌△ABP
∴PE=PB
∫In△BPE:PC-PE < CE，CE = AC-AE = AC-AB。
∴PC-PB