1 . 如图,
平面
,四边形
为直角梯形,
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/23/8aa69148-37f4-4e80-9b7c-18d091fb1a64.png?resizew=201)
(1)证明:
.
(2)若
,点E在线段
上,且
,求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd4fd4b7a4d6b8ca0c5827c055a9ce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d907751d1e01b0954e5563e8d8cbeb2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f571396be1aa4a8914a66f7d7abd6381.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080db3af81b29ed10144a1c2e2a4fb8a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/23/8aa69148-37f4-4e80-9b7c-18d091fb1a64.png?resizew=201)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8c231fb9aeaf4b73c2d835bb4c3d42b.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53e4e97a4bd7675f12f73266254dd435.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/297f713ddbcc4578e73c8afe3a52abfa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d2ed7474932ac3959108f2b835acf98.png)
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2021-03-24更新
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7卷引用:青海省海东市2020-2021学年高二上学期期末考试数学(理)试题
名校
2 . 如图,菱形
的对角线
与
交于点
,
,
,将
沿
折到
的位置使得
.
![](https://img.xkw.com/dksih/QBM/2020/12/20/2618503122452480/2620245407645696/STEM/0b073e75-d8e2-4a6a-b56b-2135a073ff76.png)
(1)证明:
.
(2)求平面
与平面
所成锐二面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d71e6ea7333dbc78d0a7b9bc3892f940.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1682d306c38087d9e6f7efb9cec596a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ac451db3443cabb204f96c31fd4a02e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fbfcae2cecc98e2d6c16dde6d3ec1c1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58fc6a5e71fa379d613ac1ef1cdf1048.png)
![](https://img.xkw.com/dksih/QBM/2020/12/20/2618503122452480/2620245407645696/STEM/0b073e75-d8e2-4a6a-b56b-2135a073ff76.png)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccbd1316b9d1f0c1e71fd078deec61f6.png)
(2)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e582d73b96ba649378379c3074d506d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80f747eb5b2d21c9de962cbfd4ec4bb7.png)
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2020-12-23更新
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10卷引用:青海省海东市2021届高三上学期第二次模拟考试数学(理)试题
青海省海东市2021届高三上学期第二次模拟考试数学(理)试题贵州省贵阳市、黔东南州部分重点高中2021届高三年级联合考试数学(理科)试题山东省日照市2021届高三下学期一模数学试题广东省梅州市蕉岭中学等三校2020-2021学年高二下学期联考数学试题甘肃省天水市第一中学2020-2021学年高三第八次模拟数学(理)试题江苏省常州市前黄高级中学2021-2022学年高三上学期期初数学试题陕西省部分重点高中2020-2021学年高三上学期12月联考理科数学试题河北省2021届高三上学期12月月考数学试题湖南省联合体2020-2021学年高三上学期12月联考数学试题湖湘名校教育联合体2022-2023学年高三上学期9月大联考数学试题
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解题方法
3 . 如图,四边形
和
都是正方形,
为
的中点,
,则直线
与平面
所成角的余弦值是( )
![](https://img.xkw.com/dksih/QBM/2020/11/21/2597859336871936/2606270172528640/STEM/66e744766957438c95205cdcb6316481.png?resizew=222)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2dde327febef2331a4766a79b433cc02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8af30416de2219fa30c651f7316a383a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06e322e0c87479bba874db9ae9ba36b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ad48b3905433001a44126e02ac8eba7.png)
![](https://img.xkw.com/dksih/QBM/2020/11/21/2597859336871936/2606270172528640/STEM/66e744766957438c95205cdcb6316481.png?resizew=222)
A.![]() | B.![]() | C.![]() | D.![]() |
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2020-12-03更新
|
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4卷引用:青海省海东市2020-2021学年高二上学期期末考试数学(理)试题