题目

It is in the room _____our meeting will be held. A. where          B. that         C. which          D. in which   答案：B   如图，四边形ABCD的对角线AC、BD交于点P，过点P作直线交AD于点E，交BC于点F．若PE=PF，且AP+AE=CP+CF．（1）求证：PA=PC．（2）若BD=12，AB=15，∠DBA=45°，求四边形ABCD的面积．