1 . 正方体
中,用平行于
的截面将正方体截成两部分,则所截得的两个几何体不可能是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11ddc92d84d188c66b435664a7e7b5a4.png)
A.两个三棱柱 | B.两个四棱台 |
C.两个四棱柱 | D.一个三棱柱和一个五棱柱 |
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2 . 2021年11月第四届中国国际进口博览会在上海举办,此届博览会共有58个国家和3个国际组织参加国际展,127个国家和地区的近3000家参展商参加企业展.各式各样的商品首次亮相上海,其中一商品的部分结构可近似看做一个多面体,如图所示.在多面体
中,底面
为直角梯形,
,侧面
为菱形,平面
平面
,M为棱
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/20/b31a5b64-2567-48ea-9232-562d302305aa.png?resizew=138)
(1)若
上有一点N满足![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
平面
,确定点N的位置并证明;
(2)若
,求平面
与平面
所成锐二面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9165d9bfbb0f0d19eb482c2a4c1b29b7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46891551c0cc4d32ed8f8007e43846b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2dde327febef2331a4766a79b433cc02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c674dc5024374f53920947c4cf4baf11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/20/b31a5b64-2567-48ea-9232-562d302305aa.png?resizew=138)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fb31ef428bd9de9bc875b343feded3c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/426ffde6bbf525078771378acc6f58d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2246c0e92e8cc344f636ea8f8f9037e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ebce46aeb97373353179e5669365fa4a.png)
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