如图,三棱柱
的棱长均为2,
为
的中点,平面
平面
,平面
平面![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d17f1396f669e6070a07115596c6bcd3.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/28/09185985-b7eb-4227-b77c-f98544036c38.png?resizew=191)
(1)求证:
平面
;
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/71f2185273bf04c11118c7954f7ec822.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/653ddc9c58281c1cc096de7c15ed0749.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9170ab5963ca15e9a35075c0781dde7f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d17f1396f669e6070a07115596c6bcd3.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/28/09185985-b7eb-4227-b77c-f98544036c38.png?resizew=191)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d020a9a555c8992a24992d63a4981bcb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/782ad39b04e9d1c7b4e774df85c53b1f.png)
更新时间:2021-03-02 08:33:50
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解答题-证明题
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【推荐1】在正三棱柱
中,
为
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/15/27e811de-5605-45cd-8b0d-5f169a7cc0c3.png?resizew=196)
(1)求证:平面
平面
;
(2)若
.
①求直线
与平面
所成角的正弦值;
②求点
到平面
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/15/27e811de-5605-45cd-8b0d-5f169a7cc0c3.png?resizew=196)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6b9a3f868837555eb40234b3375f4a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f96c673a2381f118ea2d3efc0bca1f3.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4032f71171b127da8ca7748e27580e57.png)
①求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ba9e20d667d04bf3ee7f55cc795ce01.png)
②求点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ba9e20d667d04bf3ee7f55cc795ce01.png)
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【推荐2】如图,在四棱锥
中,
,
,
,平面
平面ABCD.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/4/d8dee249-e133-4f35-aca8-f9cbba1cddcc.png?resizew=180)
(1)求证:
;
(2)已知二面角
的余弦值为
.线段PC上是否存在点M,使得BM与平面PAC所成的角为30°?证明你的结论.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/946470cef32a0bd769b3809351d8ee61.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/279e119eed905cf15026649a1b86502a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63e4d19bf237a6fca67e0d01a9ddb726.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f04c222223dae9ef27d4c132534d9848.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/4/d8dee249-e133-4f35-aca8-f9cbba1cddcc.png?resizew=180)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/545e18836bc7fee22f8f813a6f525d93.png)
(2)已知二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc9f1e2b86f4eca37c72011d3dffb0c9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64f1145c162038df3c7184d9201c628e.png)
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【推荐1】如图1,矩形ABCD中,
,将矩形ABCD折起,使点A与点C重合,折痕为EF,连接AF、CE,以AF和EF为折痕,将四边形ABFE折起,使点B落在线段FC上,将
向上折起,使平面DEC⊥平面FEC,如图2.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/8/3ce024cf-8a93-4a2d-87e6-5f9dd284a5d2.png?resizew=332)
(1)证明:平面ABE⊥平面EFC;
(2)连接BE、BD,求锐二面角A-BE-D的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ff7c2b0b38b384699cac4df6e04cc6c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d631f45bc652539853f236952afa5bbf.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/8/3ce024cf-8a93-4a2d-87e6-5f9dd284a5d2.png?resizew=332)
(1)证明:平面ABE⊥平面EFC;
(2)连接BE、BD,求锐二面角A-BE-D的正弦值.
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【推荐2】如图甲,等腰梯形ABCD中,
,
于点E,且
,将梯形沿着DE翻折,如图乙,使得A到Р点,且
.
![](https://img.xkw.com/dksih/QBM/2022/3/24/2943304209817600/2944328741183488/STEM/d948cdf2-b7e0-4b77-970a-c09c05d7b675.png?resizew=301)
(1)求直线PD与平面EBCD所成角的正弦值;
(2)若
,求三棱锥
的表面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0fff774b4b0087a6f304ce930d359be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32c38dfd14dde969702dff97ef2270f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f8beb245aee954556450e4411f3cea3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/35a5ed90e558f7f4470b43159613dbb1.png)
![](https://img.xkw.com/dksih/QBM/2022/3/24/2943304209817600/2944328741183488/STEM/d948cdf2-b7e0-4b77-970a-c09c05d7b675.png?resizew=301)
(1)求直线PD与平面EBCD所成角的正弦值;
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b006b959cd69265bb39896f53bcace43.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77ca9a104a847ed5c62421aa4c1df505.png)
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