我只能猜测图是这样的。过D作AB垂线交AB于F则AF=EF又EP=PB∴FP=AB/2=OO'又O'P=EP-EO'=(AB-AE)/2-EO'=AB/2-AE/2-EO'=AO'-EO'-DF=AE-DF=DF∠DFP=∠PO'O=90°∴△DFP≌△PO'O∴PD=POPD⊥PO
