如图,在棱长为2的正方体
中,
分别是棱
的中点,点
分别在棱
,
上移动,且
.
当
时,证明:直线
平面
;
是否存在
,使平面
与面
所成的二面角为直二面角?若存在,求出
的值;若不存在,说明理由.
![](https://img.xkw.com/dksih/QBM/2014/6/20/1571783122010112/1571783127924736/STEM/31e0debe28b14f4b9b528ee8997ef660.png)
![](https://img.xkw.com/dksih/QBM/2014/6/20/1571783122010112/1571783127924736/STEM/050ec932667949a88859bc2a1e7df91b.png)
![](https://img.xkw.com/dksih/QBM/2014/6/20/1571783122010112/1571783127924736/STEM/24c5b5897e74432f8f6ffb23e5780a8a.png)
![](https://img.xkw.com/dksih/QBM/2014/6/20/1571783122010112/1571783127924736/STEM/af01c2520a77440e8403e30e18c5723e.png)
![](https://img.xkw.com/dksih/QBM/2014/6/20/1571783122010112/1571783127924736/STEM/a306f425b305408f88c99f0380bef7a8.png)
![](https://img.xkw.com/dksih/QBM/2014/6/20/1571783122010112/1571783127924736/STEM/8698f2c903ea4cf3af99dc55b9a311a4.png)
![](https://img.xkw.com/dksih/QBM/2014/6/20/1571783122010112/1571783127924736/STEM/a79d7b02119b4432a9ded40d88a281ed.png)
当
![](https://img.xkw.com/dksih/QBM/2014/6/20/1571783122010112/1571783127924736/STEM/bdb99a01a3914d4eb2d59d5494d58bc9.png)
![](https://img.xkw.com/dksih/QBM/2014/6/20/1571783122010112/1571783127924736/STEM/516c1ee9330c430ea4494ef03d6824f9.png)
![](https://img.xkw.com/dksih/QBM/2014/6/20/1571783122010112/1571783127924736/STEM/6a056f212c454130a8714815d6a64aa5.png)
是否存在
![](https://img.xkw.com/dksih/QBM/2014/6/20/1571783122010112/1571783127924736/STEM/1d14f11dc39641f19669750777723e0a.png)
![](https://img.xkw.com/dksih/QBM/2014/6/20/1571783122010112/1571783127924736/STEM/6a056f212c454130a8714815d6a64aa5.png)
![](https://img.xkw.com/dksih/QBM/2014/6/20/1571783122010112/1571783127924736/STEM/459801040bb2479caec1e3efaac428d5.png)
![](https://img.xkw.com/dksih/QBM/2014/6/20/1571783122010112/1571783127924736/STEM/1d14f11dc39641f19669750777723e0a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/28/cfe4cfbb-cd3a-4a7f-b0ca-0d12b1496f29.png?resizew=214)
更新时间:2016-12-03 02:23:52
|
相似题推荐
解答题-证明题
|
适中
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解题方法
【推荐1】如图,在正三棱柱
中,侧棱
长为3,H、G分别为
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/5/7d7cd2b1-24e7-4f26-9cdd-4be25d880eec.png?resizew=122)
(1)求证:
平面
;
(2)若
为侧棱
上一点,且
,
与平面
所成的角为
,求此三棱柱的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9be21bca03babeda11d70f7483a86f89.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/5/7d7cd2b1-24e7-4f26-9cdd-4be25d880eec.png?resizew=122)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4193fb98c610f41f9a6c89d046f13d32.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e168672b47d7e64dc1b404f8882c7dcf.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98823cbc09ca52df1fbcc446eba3e44f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ad3a1ea6790177130e16c2124984087.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9edc50f7febbc2d5d8dcdc23a3630a7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20b69099d2b74ffbb1f365e1468bd8fa.png)
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【推荐2】如图,在几何体中,四边形
是菱形,
是矩形,平面
平面
,
为
中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/17/a3569ed6-82a2-4552-9cbe-17039c9038ce.png?resizew=241)
(1)求证:
平面
;
(2)求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a3ab4fdfc612c9fa2dd8ae24904192d8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b61804389aabf1e02857b748dd103700.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/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/17/a3569ed6-82a2-4552-9cbe-17039c9038ce.png?resizew=241)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/250833a6c405ffd724b673b478c22919.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/711da913d92fc989e581bcfdfe092a18.png)
(2)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/adf21399dcf3682bf5d3f9cbd5eed86c.png)
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【推荐3】如图,正三棱柱ABC﹣A1B1C1的底面边长是2,侧棱长是
,D是AC的中点.
![](https://img.xkw.com/dksih/QBM/2021/6/17/2744725134147584/2745703851720704/STEM/049ba30fb5d2458aa6b0af52b7e08b71.png?resizew=285)
(1)求证:B1C∥平面A1BD;
(2)求二面角A﹣A1B﹣D的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
![](https://img.xkw.com/dksih/QBM/2021/6/17/2744725134147584/2745703851720704/STEM/049ba30fb5d2458aa6b0af52b7e08b71.png?resizew=285)
(1)求证:B1C∥平面A1BD;
(2)求二面角A﹣A1B﹣D的余弦值.
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解题方法
【推荐1】如图,在多面体ABCDEF中,平面
平面ABCD,
,
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/18/ac6f0d86-db40-4188-84c0-b0c96fc5749a.png?resizew=161)
(1)求证:
;
(2)若四边形ACEF为正方形,在线段AF上是否存在点P,使得二面角
的余弦值为
?若存在,请求出线段AP的长;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2a4e3f0349fa83dc2a0b7d798f04843.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4adf90a8c2b29334cdc5aa5b554991f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1134c8e3440abb6cd385af2c169037fe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09d27bd71d79cb19eb554175e4ef0867.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/829018a6ca0aff95d89e3f7cd943274e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/18/ac6f0d86-db40-4188-84c0-b0c96fc5749a.png?resizew=161)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/70c5fd65265f85df7d149d83d80d4e62.png)
(2)若四边形ACEF为正方形,在线段AF上是否存在点P,使得二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/053af8641980763a7f0e77beefe0712d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf31876698721a199c7c53c6b320aa86.png)
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【推荐2】如图,在四棱锥
中,平面
平面
,
,四边形
为菱形,
.
![](https://img.xkw.com/dksih/QBM/2022/3/9/2932628723941376/2936590253531136/STEM/37931538-8d61-48ee-96ea-289abadfd55a.png?resizew=177)
(1)证明:
.
(2)已知
,平面
与平面
的夹角为45°,求四棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4aa9084b8fe0fe05c4388d1f835587b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63e4d19bf237a6fca67e0d01a9ddb726.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f945a69cf7e8213e50622125cde652f5.png)
![](https://img.xkw.com/dksih/QBM/2022/3/9/2932628723941376/2936590253531136/STEM/37931538-8d61-48ee-96ea-289abadfd55a.png?resizew=177)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c583493109d50c9e4634c05e9042a9f.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e582d73b96ba649378379c3074d506d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80f747eb5b2d21c9de962cbfd4ec4bb7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
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【推荐3】如图1,在矩形ABCD中,AB=2,BC=1,E是DC的中点,将
沿AE折起,使得点D到达点P的位置,且PB=PC,如图2所示.F是棱PB上的一点.
![](https://img.xkw.com/dksih/QBM/2022/11/25/3117365887442944/3118614445211648/STEM/5f34a0cf0c7f46548f90ff0a7a2e3f17.png?resizew=431)
(1)若F是棱PB的中点,求证:
平面PAE;
(2)是否存在点F,使得二面角
的余弦值为
?若存在,则求出
的值;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63b43490ca09467a4c8cd8cfe91c94e4.png)
![](https://img.xkw.com/dksih/QBM/2022/11/25/3117365887442944/3118614445211648/STEM/5f34a0cf0c7f46548f90ff0a7a2e3f17.png?resizew=431)
(1)若F是棱PB的中点,求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94270844f197d524bf1da4f1385befd2.png)
(2)是否存在点F,使得二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f726924c16c769a012d7a111f81e44e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/afd3f14f202cd26f36711eefcdc03103.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d3c24c0a11fa3e09841f884ba666043.png)
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