如图,在直三棱柱ABC-A1B1C1(侧棱和底面垂直的棱柱)中,平面A1BC⊥侧面A1ABB1,AB=BC=AA1=3,
如图,在直三棱柱ABC-A1B1C1(侧棱和底面垂直的棱柱)中,平面A1BC⊥侧面A1ABB1,AB=BC=AA1=3,线段AC、A
如图,在直三棱柱ABC-A
1B
1C
1(侧棱和底面垂直的棱柱)中,平面A
1BC⊥侧面A
1ABB
1,AB=BC=AA
1=3,线段AC、A
1B上分别有一点E、F且满足2AE=EC,2BF=FA
1.
(1)求证:AB⊥BC;
(2)求点E到直线A
1B的距离;
(3)求二面角F-BE-C的平面角的余弦值.