正方体
的棱长为1.
(1)
为
中点,求异面直线
与
所成的角的大小;
(2)求二面角
的大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3da8c338342e38c9aa3f274c053fd5b.png)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20ecac2dad4cffdd971fd23deacff3fc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5d9c105f5558d48cc42218ed2b3ef4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9601d29de0a884953b039ee72f0158fe.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bcab96a77dca8fecea17cbc9a2278748.png)
更新时间:2022-12-13 19:04:41
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解答题-问答题
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解题方法
【推荐1】如图所示,甲船在距离
港口24海里,并在南偏西20°方向的
处驻留等候进港,乙船在
港口南偏东40°方向的
处沿直线行驶入港,甲、乙两船距离为31海里.
![](https://img.xkw.com/dksih/QBM/2021/6/29/2753293086367744/2781000254832640/STEM/f6c277da-af37-4f72-a560-65fae21b6162.png?resizew=236)
(1)求
的大小;
(2)当乙船行驶20海里到达
处,接到港口指令,前往救援忽然发生火灾的甲船,此时甲、乙两船之间的距离为多少?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://img.xkw.com/dksih/QBM/2021/6/29/2753293086367744/2781000254832640/STEM/f6c277da-af37-4f72-a560-65fae21b6162.png?resizew=236)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
(2)当乙船行驶20海里到达
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
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【推荐2】如图,在直角梯形ABCD中,AD//BC,
,当E、F分别在线段AD、BC上,且
,AD=4,CB=6,AE=2,现将梯形ABCD沿EF折叠,使平面ABFE与平面EFCD垂直.
(1)判断直线AD与BC是否共面,并证明你的结论;
(2)当直线AC与平面EFCD所成角为多少时,二面角A—DC—E的大小是60°.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/45acdbac251ca6b76a166c1242e71df9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58cc90fee532e50d319081d571410421.png)
(1)判断直线AD与BC是否共面,并证明你的结论;
(2)当直线AC与平面EFCD所成角为多少时,二面角A—DC—E的大小是60°.
![](https://img.xkw.com/dksih/QBM/2010/4/6/1569691187535872/1569691192360960/STEM/0b252f9b-c573-4ca2-9bc3-2dcafbecd8b8.png?resizew=546)
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【推荐3】如图,在四棱锥
中,底面
为正方形,
平面
,
为
上的中点.
平面
;
(2)设
,求二面角
的大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](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/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30067b7b236d17af8a462f96a58d11bd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46e2da608b66c9aee03e2503388ba4fd.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e7b6d04f024ca05cdfacc8ce9137c15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbeab80976db9b4689b9446cda06196a.png)
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【推荐1】如图,已知四棱锥P-ABCD,底面ABCD为菱形,PA⊥平面ABCD,∠ABC=60°,E,F分别是BC,PC的中点.
![](https://img.xkw.com/dksih/QBM/2019/12/16/2356267972648960/2356592189448192/STEM/2b131ef6fe4b4824b51b1de80626e57b.png?resizew=173)
(I)证明:AE⊥PD;
(II)设AB=PA=2,
①求异面直线PB与AD所成角的正弦值;
②求二面角E-AF-C的余弦值.
![](https://img.xkw.com/dksih/QBM/2019/12/16/2356267972648960/2356592189448192/STEM/2b131ef6fe4b4824b51b1de80626e57b.png?resizew=173)
(I)证明:AE⊥PD;
(II)设AB=PA=2,
①求异面直线PB与AD所成角的正弦值;
②求二面角E-AF-C的余弦值.
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【推荐2】如图,已知四边形ABCD由Rt△ABC和Rt△BCD拼接而成,其中∠BAC=∠BCD=90°,∠DBC=30°,AB=AC,
,将△ABC沿着BC折起,
![](https://img.xkw.com/dksih/QBM/2020/1/9/2379137620656128/2425277076406272/STEM/fbf438cae568434fac706338aeb84395.png?resizew=222)
(1)若
,求异面直线AB和CD所成角的余弦值;
(2)当四面体ABCD的体积最大时,求二面角A﹣BC﹣D的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d795c979b744dabc38abe3f84ad433bb.png)
![](https://img.xkw.com/dksih/QBM/2020/1/9/2379137620656128/2425277076406272/STEM/fbf438cae568434fac706338aeb84395.png?resizew=222)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7fb054f095b1f977680703324ef904d0.png)
(2)当四面体ABCD的体积最大时,求二面角A﹣BC﹣D的余弦值.
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【推荐1】如图,点
分别为圆柱下底面圆周上的三个等分点,
,
,
分别为圆柱的三条母线,点
分别为母线
,
上的点,且
,点M是
的中点.
![](https://img.xkw.com/dksih/QBM/2022/4/19/2961618738192384/2962928964345856/STEM/86e49fad-1054-4319-a299-498bbfb9d6c8.png?resizew=128)
(1)证明:BM⊥平面
.
(2)求平面
与平面
所成锐二面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce7af7c5df749c6fa9bbe87faa72c66d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a373959bb9026f8a09845c0b828bf82.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/270fc011a543da83acf704f718fe9618.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://img.xkw.com/dksih/QBM/2022/4/19/2961618738192384/2962928964345856/STEM/86e49fad-1054-4319-a299-498bbfb9d6c8.png?resizew=128)
(1)证明:BM⊥平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b03428a8f91a5674cb8f54766c165f7e.png)
(2)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b03428a8f91a5674cb8f54766c165f7e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e975f6c9fafab8fd7639dc0cd0f70a4.png)
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【推荐2】如图,四边形
是平行四边形,且
,四边形
是矩形,平面
平面
,且
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/24/2cde64b6-ddc9-4bce-9dd3-07eb53033121.png?resizew=177)
(1)求证:
平面
;
(2)求平面
与平面
所成的锐二面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5e35225f4d153a40ff5a6485590805a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd4b93d7abcfc4c3df48f03aa969c17f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2a4e3f0349fa83dc2a0b7d798f04843.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22437a2a3402609bfd4054a9f2b6c685.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/24/2cde64b6-ddc9-4bce-9dd3-07eb53033121.png?resizew=177)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca5dd496ee0c1170ef6dcc48266ee444.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6541c0cb89f08aa4c937c0beb915e0a7.png)
(2)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87c0bfeadcf17b2a45896071f07a4a5a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10fc7991ea17d54ff5f4445ac5699463.png)
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【推荐3】如图,在正三棱柱
中,
分别是
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/12/5fe45a29-3d25-4702-b808-4ee42a8c6dc8.png?resizew=199)
(1)求证:
平面
;
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9ceb5fa229a5c80e3e50a428a06cb63.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ddef39ef9ed3da136c4ed8b5d28b73e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/12/5fe45a29-3d25-4702-b808-4ee42a8c6dc8.png?resizew=199)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06222ee533c2484ab25321a6abbf98cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d9a8181f7a7fe7f3fac872ce9534f15.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77a34e44c5d7e1d22521fb293994f5b0.png)
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