在如图所示的试验装置中,两个正方形框架ABCD,ABEF的边长都是1,且它们所在的平面互相垂直.活动弹子M,N分别在正方形对角线AB,BF上移动,且CM,BN的长度保持相等,记
.
(1)求异面直线AC,BF所成角的余弦值;
(2)a为何值时,MN的长最小?
(3)当MN的长最小时,求AB与平面AMN夹角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ec6a9edd2407d0bb7a628a8f2a27c9a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/19/551f2680-acd4-4e5d-9ad2-3a6518707afb.png?resizew=124)
(1)求异面直线AC,BF所成角的余弦值;
(2)a为何值时,MN的长最小?
(3)当MN的长最小时,求AB与平面AMN夹角的余弦值.
更新时间:2023-10-30 00:50:08
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【推荐1】如图,在四棱锥P—ABCD中,底面ABCD为正方形,PA⊥底面ABCD,PA=AB,E为线段PB的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/29/1892d0ea-50bc-44a0-8a44-a71261c9fc4e.png?resizew=165)
(1)若F为线段BC的中点,求异面直线EF与PD所成角的余弦值;
(2)证明:点F在线段BC上移动时,△AEF始终为直角三角形.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/29/1892d0ea-50bc-44a0-8a44-a71261c9fc4e.png?resizew=165)
(1)若F为线段BC的中点,求异面直线EF与PD所成角的余弦值;
(2)证明:点F在线段BC上移动时,△AEF始终为直角三角形.
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【推荐2】如图,在直三棱柱
中,平面
侧面
,且
.
![](https://img.xkw.com/dksih/QBM/2022/5/12/2977926689128448/2980203028733952/STEM/2109c147-edc9-4af5-9e07-d7200866e2f3.png?resizew=181)
(1)求证:
平面
;
(2)若
,求
与AC所成角的余弦值
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21dee56b9f36ba8f76fe67b76383636b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31e53b212640dadf751ef7f65a78a209.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc633603ce426facfd47d2bca6a90dbb.png)
![](https://img.xkw.com/dksih/QBM/2022/5/12/2977926689128448/2980203028733952/STEM/2109c147-edc9-4af5-9e07-d7200866e2f3.png?resizew=181)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2ffc6952e988d04f22f0fb2f7f0ab7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31e53b212640dadf751ef7f65a78a209.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e65a3e478bb87d094e3a0af30dd10ae8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e26d9636ad77369535852c6e4493446a.png)
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【推荐1】如图,在三棱锥
中,已知
平面ABC,
,
,D为PC上一点,且
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/16/596607b1-7bdb-44f4-b321-6c45cae4f8b5.png?resizew=179)
(1)求AC的长;
(2)若E为AC的中点,求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd4fd4b7a4d6b8ca0c5827c055a9ce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f83a04565a8ebaa111894b724b0ba266.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c06154cae3bf7a8ce5a1e97a7380875.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e73929198cc43a209deb1ae9bc0841a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e4125524caac016727c80d2722c5ba3.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/16/596607b1-7bdb-44f4-b321-6c45cae4f8b5.png?resizew=179)
(1)求AC的长;
(2)若E为AC的中点,求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a879800a059ce741a99bb2c171f32afe.png)
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【推荐2】如图,直三棱柱
,底面
中,
,
,棱
,
、
分别是
、
的中点.
![](https://img.xkw.com/dksih/QBM/2011/4/28/1570133485240320/1570133490515968/STEM/50c7e71af33441f9ba214a438ce7d209.png?resizew=151)
(1)求
的长;
(2)求
的值;
(3)求证:
;
(4)求
与平面
所成的角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca38004c7744a7567bef30f0674fe60f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97e89a358226b4be8786077a60555c69.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92535536bd3c2761724fd058427f95a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11ddc92d84d188c66b435664a7e7b5a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a696a182fff038a86b2bbe8ca099442.png)
![](https://img.xkw.com/dksih/QBM/2011/4/28/1570133485240320/1570133490515968/STEM/50c7e71af33441f9ba214a438ce7d209.png?resizew=151)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f847a413b630a37a33b071c6c32ef126.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2838d623f4ebb778514bd1575ef23cc3.png)
(3)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24b201f1e798eb74963b98f2b0da4132.png)
(4)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fd4c85bb98a2a0afddd7ed92578ad2e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9b7b7793d29d66dfdd89e7a6564a35c.png)
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【推荐1】如图,在正四棱锥
中,
,
,
分别为
,
的中点.
![](https://img.xkw.com/dksih/QBM/2017/4/12/1664078945124352/1664181740625920/STEM/1d061c61aa8442a2b5052206f937ae39.png?resizew=292)
(1)求证:
平面
;
(2)求异面直线
与
所成角的余弦值;
(3)若平面
与棱
交于点
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/829f9180ddd9aa1a0ee0dc520f4e0b5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://img.xkw.com/dksih/QBM/2017/4/12/1664078945124352/1664181740625920/STEM/1d061c61aa8442a2b5052206f937ae39.png?resizew=292)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e56fdf217165748fafe938b64fa08179.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f571a1aac46c6d0cf440c0ec2846bf9.png)
(2)求异面直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
(3)若平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b03428a8f91a5674cb8f54766c165f7e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0519ba613bf121a2c1bc28c948266d74.png)
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【推荐2】如图所示,在正方体
中,点
,
分别在
,
上,且
,
,求
与
所成角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c6151468904c32d230da58dca8193a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/522230546d4b802094e86ceb48c2ba38.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5076289823db419f94e9c0c8f4aafd9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11ddc92d84d188c66b435664a7e7b5a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f66fb71b75b63594ebeeeebd1963eed5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df4fcbc9ca7fc86a40dfc91ed20511db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4be3e50e2041a385c23873fd25e09957.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c54dc0ff58e8c7d1035c2dff8572b30f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8c1dd5a3f83a7455eb3630364397accc.png)
![](https://img.xkw.com/dksih/QBM/2020/12/7/2609053221830656/2612762365345792/STEM/d25c9873034445958c306899b04678f5.png?resizew=161)
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【推荐3】如图,在四棱锥
中,
底面
,底面
为直角梯形,且
,
,若
.
![](https://img.xkw.com/dksih/QBM/2021/12/24/2879278804713472/2893085838041088/STEM/d59472e3-dc86-4089-a498-3af86117ac29.png?resizew=214)
(1)求证:
平面
;
(2)求异面直线
与
所成的角的余弦值;
(3)求平面
与平面
所成夹角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.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/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34e0a957a55460c72673c0f2ee90dbb3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/45acdbac251ca6b76a166c1242e71df9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5730ee74df7d277d066310385c62a2f8.png)
![](https://img.xkw.com/dksih/QBM/2021/12/24/2879278804713472/2893085838041088/STEM/d59472e3-dc86-4089-a498-3af86117ac29.png?resizew=214)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97f30533da2e1d2a958dc906c37eba9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0628681907ac8d7fdb94d8bc1b15feb9.png)
(2)求异面直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
(3)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/852aabd89edffc1b94344ff3f1f31ccd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80f747eb5b2d21c9de962cbfd4ec4bb7.png)
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【推荐1】如图:三棱锥
中,
平面
,且
,
;
,
,垂足分别为
,
.
![](https://img.xkw.com/dksih/QBM/2020/12/1/2605011111460864/2606904181825536/STEM/c9bd710992e141678536c0e0cfb7b815.png?resizew=227)
(1)求证:
为直角三角形;
(2)求直线
与平面
所成角的大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/891579e7c231584a8e16b8eeff79888e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21f9157fce2a8339d281178c7c0bccbe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca67a5b8f69507c8b80379e86f90a8ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f177e3147f92fdd121ab472d80943f0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f144992e1cbee34868abce1e5ad38c9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d3f843b83e62bab294988a7ea134a63.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/40530164525a08a8e3de3d5d09d83dc8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://img.xkw.com/dksih/QBM/2020/12/1/2605011111460864/2606904181825536/STEM/c9bd710992e141678536c0e0cfb7b815.png?resizew=227)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98013a5042685a1db94249e70c62c09a.png)
(2)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/212a67f115d1cbe69f100b489babe5f8.png)
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解题方法
【推荐2】如图,在直棱柱
中,
,
,点
、
、
分别是
、
、
的中点.
(1)求
与平面
所成角的大小;
(2)求
到平面
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b090de03b3f6e42942359ce8d1fd5a15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36c4559d27e3905980d1a4f1856f07de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11ddc92d84d188c66b435664a7e7b5a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/9/14/b3ccca67-6af5-47dc-a401-4f87c76fa471.png?resizew=134)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/134ef0b1a2669a09f05bd4dc2496f706.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/134ef0b1a2669a09f05bd4dc2496f706.png)
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