解答:(1)证明:过点D作DF∥AC交BC于点F,
∴∠ACB=∠DFB,∠FDP=∠E
∵AB=AC(已知),
∴∠ACB=∠ABC,
∴∠ABC=∠DFB,
∴DF=DB;
又∵CE=BD(已知),
∴CE=DF;
又∵∠DPF=∠CPE,
∴△ECP≌△DFP,
∴PE=PD;
(2)解:∵CE=BD,AC=AB,CE:AC=1:5(已知),
∴BD:AB=1:5,
∵DF∥AC,
∴△BDF∽△BAC,
∴
=BF BC
=BD BA
;1 5
∵BC=10,
∴BF=2,FC=8,
∵△DFP≌△ECP,
∴FP=PC,
∴PF=4,
则BP=BF+FP=6.