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、A1B上分别有一点E、F且满足2AE=EC,2BF=FA1.
(1)求证:AB⊥BC;
(2)求点E到直线A1B的距离;
(3)求二面角F﹣BE﹣C的平面角的余弦值.
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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、A1B上分别有一点E、F且满足2AE=EC,2BF=FA1.
(1)求证:AB⊥BC;
(2)求点E到直线A1B的距离;
(3)求二面角F﹣BE﹣C的平面角的余弦值.