解题方法
1 . 如图1,在四边形
中,
,
,
为
中点,将
沿
折到
的位置,连结
,
,如图2.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/13/b8dd3eb7-4ed8-44f3-ba0d-1205f526f18d.png?resizew=376)
(1)求证:
;
(2)若
,求平面
与平面
所成锐二面角的大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f79863ffcfa63117ca6741b20a48e69.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d33944eaeb9a0827d1c3843ba7e7d997.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cd51caff8d6cd6d3478fb4659789d8d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11619b58a743ef65ce5340686096fa40.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d4db9b82b67efe45a02fca32bfcf5dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c2bc5e50b8dfa02601c70822252854a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/13/b8dd3eb7-4ed8-44f3-ba0d-1205f526f18d.png?resizew=376)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/25326f1dd012551315df3c0e1f5dd396.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e851cf27f94ac130d849e0b83af75528.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32b74a32c8ccd8a3632c8d79e5eb51cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21665d21bbfb04410c78345de1fd15ae.png)
您最近一年使用:0次
11-12高三·甘肃兰州·期末
2 . 如图,已知正三棱柱ABC=A1B1C1的各棱长都是4,E是BC的中点,动点F在侧棱CC1上,且不与点C重合.
(1)当CF=1时,求证:EF⊥A1C;
(2)设二面角C﹣AF﹣E的大小为θ,求tanθ的最小值.
(1)当CF=1时,求证:EF⊥A1C;
(2)设二面角C﹣AF﹣E的大小为θ,求tanθ的最小值.
![](https://img.xkw.com/dksih/QBM/2014/5/30/1571743289548800/1571743295217664/STEM/f5366a5d-1b73-4a44-83e1-0a534c239eda.png?resizew=232)
您最近一年使用:0次
2016-12-03更新
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2156次组卷
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5卷引用:2016届福建省三明一中高三上第二次月考理科数学试卷