过E做EH//PB H在AB上∵正方形ABCD中,点P为对角线AC上的任意一点∴PE=AE=DF=BHAE+ED=AD=AB=AH+HB∴ED=AH∵∠HAE=∠EDF=90°∴△AHE≌△DEF∴∠AEH+∠DEF=90°∴HE⊥EF∵HE//BP∴BP⊥EF