三棱锥被平行于底面ABC的平面所截得的几何体如图所示,截面为A1B1C1,∠BAC=90°,A1A⊥平面ABC,A1A=
,AB=
,AC=2,A1C1=1,
.
(1)证明:BC
A1D;
(2)求二面角A-CC1-B的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0870515b612ef842f01f3b5eeca220b5.png)
(1)证明:BC
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1633988fd62a652de726ee92a917b52d.png)
(2)求二面角A-CC1-B的余弦值.
![](https://img.xkw.com/dksih/QBM/2018/3/6/1896189515472896/1903293946019840/STEM/d95a5686-1951-4424-b8ac-4229e9b94db3.png)
更新时间:2018-03-16 11:24:21
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适中
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d077f6da8b2c00b152d4679aa2ed7f7.png)
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解题方法
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适中
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适中
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【推荐3】如图,
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