如图,在直三棱柱
中,
,点
分别为棱
的中点.
(Ⅰ)求证:
∥平面![](https://staticzujuan.xkw.com/quesimg/Upload/formula/134ef0b1a2669a09f05bd4dc2496f706.png)
(Ⅱ)求证:平面
平面
;
(Ⅲ)在线段
上是否存在一点
,使得直线
与平面
所成的角为300?如果存在,求出线段
的长;如果不存在,说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2498b78493e5ba9c3c4dd582e866e76b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/927456b0989846a2f1573844bbaa2105.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76f5d2788b1a3e32741f3261d10016e5.png)
(Ⅰ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24bb49fdc6b6bbb2449fdf8a0de769d3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/134ef0b1a2669a09f05bd4dc2496f706.png)
(Ⅱ)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/803fa75db3ac3a26a41e347dc4165026.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/134ef0b1a2669a09f05bd4dc2496f706.png)
(Ⅲ)在线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fd17a66a2af938c89e46f22e4d893b1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13cfdc6224181d44e63aab43ddaf07ef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/12/e61afd66-a3a2-4a15-afe5-66b352239fc5.png?resizew=192)
更新时间:2019-04-04 21:29:44
|
相似题推荐
解答题-问答题
|
适中
(0.65)
【推荐1】如图,三棱柱ABC-A1B1C1中,平面ABB1A1⊥底面ABC,
,∠A1AB=120°,D、E分别是BC、A1C1的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/1/81a2e6d8-a983-4cb5-9d0c-55cf143fb2a3.png?resizew=216)
(Ⅰ)试在棱AB上找一点F,使
平面A1CF;
(Ⅱ)在(Ⅰ)的条件下,求二面角A-A1C-F的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c0da60f7d50768d34bdc59759c4b0b66.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/1/81a2e6d8-a983-4cb5-9d0c-55cf143fb2a3.png?resizew=216)
(Ⅰ)试在棱AB上找一点F,使
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b78172568aac9805d2ea2d5f742bf80c.png)
(Ⅱ)在(Ⅰ)的条件下,求二面角A-A1C-F的余弦值.
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解题方法
【推荐2】如图,在四棱锥
中,
平面ABCD,
,
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/30/d389701a-0f40-4959-9ba2-0b22bb495627.png?resizew=139)
(1)若E为PA的中点,求证
平面PBC;
(2)求四棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5f1897a7e856b42f8cee0f286ad913d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68d31600cba2d5256c7e78b6122d6755.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/78feced8260265bc763742f89dbc33d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ffc2817fa590affb5a760a25dc65308.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be41b05e11ba5eadaaed9a224b949774.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/30/d389701a-0f40-4959-9ba2-0b22bb495627.png?resizew=139)
(1)若E为PA的中点,求证
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/063510e3c1fb6a7ccc3b8e3e3c7d660e.png)
(2)求四棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
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解题方法
【推荐1】如图所示,
平面ABC,
平面ABC,
,
,
,F为BC的中点.
(1)求证:
平面BDE;
(2)求凸多面体ABCED的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca5dd496ee0c1170ef6dcc48266ee444.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44b190c8d3d7d7d0e6e959e8a52eae90.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5359ad5437bb4605bea0dc58da9b94b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f144992e1cbee34868abce1e5ad38c9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0761165f1176f3a5fe4f7b052832316d.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/3/32ae021c-b747-4a26-8d18-363ea0c5fa31.png?resizew=149)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2dcafa398cc6b6079883e7ad153eb62d.png)
(2)求凸多面体ABCED的体积.
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解题方法
【推荐2】如图,直三棱柱
中,
,
,D,E分别是
,
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/1/1164b1a9-94fd-47a2-ad15-6b2c94724b71.png?resizew=168)
(1)证明:平面
平面
;
(2)求三棱锥
的高.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ac4fb99967c46a3855bcf2885b448c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f90e17995e2f71e297d94ae51c7e5b1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c1ac2e11788860424508ea9e80cf89d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbb16f7dbc4b9993c4efa0764df1d8ca.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/1/1164b1a9-94fd-47a2-ad15-6b2c94724b71.png?resizew=168)
(1)证明:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2340abb56da9c571b7f17bb21cabe010.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9a32bd7a1b78b5a0ec562c4025aea8c.png)
(2)求三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d589c7f5ed8b617abed55067bd833ab.png)
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解题方法
【推荐1】四棱锥
中,
面
,
,
,
是
的中点,
在线段
上,且满足
.
(1)求证:
平面
;
(2)求二面角
的余弦值;
(3)在线段
上是否存在点
,使得
与平面
所成角的余弦值是
,若存在,求出
的长;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a1b49f64e0065edad868b25e9fcada3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/600e47e5295f977e400f025bfd9eda98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b63181e1512d862f309439a7408bef51.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd33764ff4efddfe11a98a609753715c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fbae68020a497f0c021bea162bcebaf.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/5/29/39632c8b-a5e4-44c8-a065-eefc2e57b84f.png?resizew=158)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7440b41636c761b0910639e310ff7dfb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b7c83470489253394bd288d7c920df.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60aa084359c6919653fdcbd2f4c26ede.png)
(3)在线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd33764ff4efddfe11a98a609753715c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/632917e61f4208959686d118c7f19231.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ee72fd8a5a52d08a4fddcf0830a8e103.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1174142f3bba761585b6bc2653009b36.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84d454c82d9e52747563d47b68099249.png)
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【推荐2】如图,在三棱柱
中,平面
平面
,
是边长为2的正三角形,
是
的中点,
,直线
与平面
所成的角为
.
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/df00cdf77ed39ca5a0b305861a693142.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3c65edad25ddd666cdce0d7e5afefc9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91cbafbd47a57b0a24799ca61af682f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e26d9636ad77369535852c6e4493446a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31e53b212640dadf751ef7f65a78a209.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/79a97bb4dcfab4ec7539bc783d563c49.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb689000fa7a3b425be3196d8b0f32af.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/74bca84ad86c648d3bb20c8909c8da3f.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c05af9606b7540ab585d7556be2ebafe.png)
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【推荐3】在四棱锥
中,底面
是边长为
的正方形,
平面
为
中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/12/9483759d-98fd-46f1-86dc-b6cb0fc9806d.png?resizew=146)
(1)如果
与平面
所成的线面角为
,求证:
平面
.
(2)当
与平面
所成角的正弦值最大时,求三棱锥
的体积.
![](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/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a1b49f64e0065edad868b25e9fcada3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dfaefb10f82b89802bb420b3c41de1bd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/12/9483759d-98fd-46f1-86dc-b6cb0fc9806d.png?resizew=146)
(1)如果
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd33764ff4efddfe11a98a609753715c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15615de1a6df206dbd081251f676578e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5f1897a7e856b42f8cee0f286ad913d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ddb7c2ca1b6bee86cb24fed02e40da2.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cdba1337ec85fa9722cb4b320a82ae6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bc46688d8723cf2003fc25890265200.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/076fdb31d17c86dbdc53da175c6ae90b.png)
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