例、如图所示,在正方体ABCD-A1B1C1D1中,E为棱BC的中点.

(1)求证:BD1//平面C1DE;
(2)试在棱CC1上求一点P,使得平面A1B1P⊥平面C1DE.
解析:
(1)如图a所示,建立空间直角坐标系Dxyz,设正方体棱长为1,

则D(0,0,0),D1(0,0,1),E(
,1,0),B(1,1,0),C1(0,1,1),
=(-1,-1,1),
=(0,1,1),
=(
,1,0).

(2)易知A1B1⊥平面B1C,∴A1B1⊥C1E,要平面A1B1P⊥平面C1DE,只要C1E⊥平面A1B1P即可,则要C1E⊥B1P.
P在C1C上,设P的坐标为P(0,1,t),则
=(-1,0,t-1).
.
即P(0,1,t),∴P在CC1的中点时可使得平面A1B1P⊥平面C1DE.