名校
1 . 如图所示,已知长方体
中,
,
为
的中点,将
沿
折起,使得
.
![](https://img.xkw.com/dksih/QBM/2017/3/31/1655498603372544/1655671527243776/STEM/eedf1d77f8c146b3be95190bb8c18d65.png?resizew=531)
(1)求证:平面
平面
;
(2)是否存在满足
的点
,使得二面角
为大小为
?若存在,求出相应的实数
;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/100af11e6cb83b56437f2db7dadeb9f4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e1e88b36ff71fe69c07bade0f95f1ef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/804c0e2a375b5f4ff1c420532968efc3.png)
![](https://img.xkw.com/dksih/QBM/2017/3/31/1655498603372544/1655671527243776/STEM/eedf1d77f8c146b3be95190bb8c18d65.png?resizew=531)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0bb5012f6c70a1e98d682b6d021fadd8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0760712e3e2ea02b755b751e760d0c55.png)
(2)是否存在满足
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eaac8d2b8d350312c425b4f0dc5b8cd8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a5266895d3c1fcb350a745bc779433b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af9955b5aebb73cd84447e8541f901ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
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2017-03-31更新
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1378次组卷
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4卷引用:河南省息县第一高级中学2017届高三下学期第二次阶段测试理数试题
2 . 已知四棱锥
中,底面是直角梯形,
,
,
,侧面
是以
为直角的等腰三角形,且侧面
与底面
垂直.
![](https://img.xkw.com/dksih/QBM/2017/4/28/1675418249404416/1679795616350208/STEM/0a55b9bceab348ea888a11f46172fcb3.png?resizew=222)
(I)求证:
;
(II)若点
为侧棱
上的一动点,问点
在何位置时,二面角
的余弦值为
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faeb97acf19bd3b2c6c77c2814df4d2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e921f46d90e43f4517c55832b6280f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8af620f6d204d310d8e3f267fdd6c3f8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d923a338dd2d2e29336b42574d38448.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c52e7222eb3978fd85e743d084a9e5a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d923a338dd2d2e29336b42574d38448.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://img.xkw.com/dksih/QBM/2017/4/28/1675418249404416/1679795616350208/STEM/0a55b9bceab348ea888a11f46172fcb3.png?resizew=222)
(I)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0fe0bb7d51e559e73aa16a954fe7fa33.png)
(II)若点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d4db9b82b67efe45a02fca32bfcf5dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/977c07a8bc54f8d1ad72cd9048058afc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dee14db57f0c762aad845cf5b4a243c0.png)
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