∵∠ACB=90°,AB=15,BC=9,
∴AC=
=
AB2?BC2
=12,
152?92
∵AD=DC,DF⊥AC,
∴AF=CF=
AC=6,1 2
∴点C关于DE的对称点是A,故E点与P点重合时△BCP的周长最小,
∴DP=DE,
∵DE⊥AC,BC⊥AC,
∴DE∥BC,
∴△AEF∽△ABC,
∴
=AF AC
,即AE AB
=6 12
,解得AE=AE 15
,15 2
∵DE∥BC,
∴∠AED=∠ABC,
∵∠DAB=∠ACB=90°,
∴Rt△AED∽Rt△CBA,
∴
=AE BC
,即DE AB
=
15 2 9
,解得DE=DE 15
=12.5,即DP=12.5.25 2
故选B.