在三棱柱
中,
平面ABC,
,
,D,E分别为AB,
中点.
![](https://img.xkw.com/dksih/QBM/2020/2/18/2401669017673728/2401756928532480/STEM/9e80eaf1-9472-4e7a-bf4b-2f402aa2c923.png?resizew=165)
(Ⅰ)求证:
平面
;
(Ⅱ)求证:四边形
为平行四边形;
(Ⅲ)求证:平面
平面
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a8bfe2553e852df73185d017c0a62fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/615fc8790237a1b09af51d6bcad6b595.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b10134e7a46e6f6f7cb9d5e2371727d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11ddc92d84d188c66b435664a7e7b5a4.png)
![](https://img.xkw.com/dksih/QBM/2020/2/18/2401669017673728/2401756928532480/STEM/9e80eaf1-9472-4e7a-bf4b-2f402aa2c923.png?resizew=165)
(Ⅰ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e56fdf217165748fafe938b64fa08179.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58cc6184b191e6da43911e701121517e.png)
(Ⅱ)求证:四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f78bd7f2e3d25d79c3e09f896ee1d731.png)
(Ⅲ)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/140088b0cb73812aa9d523c44559298a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f78bd7f2e3d25d79c3e09f896ee1d731.png)
更新时间:2020-02-18 17:29:53
|
相似题推荐
解答题-证明题
|
适中
(0.65)
【推荐1】如图,四棱锥
中,底面
为直角梯形,
,平面
平面
,
分别为
的中点,
为
的中点,过
作平面
分别与交
于点
.
(Ⅰ)当
为
中点时,求证:平面
平面
;
(Ⅱ)当
时,求三棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faeb97acf19bd3b2c6c77c2814df4d2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b8bfc02053ff413c76e2474a94793b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/235d1553f6806c1eee3b17b94d23f0f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4cd8d4e787ff35524d2beab499ec632.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b81c01cc7eda0e228f6e2698a009cfb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7789a500686c7a73770404ead6af0590.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/389bc3f29c058067e06e0d0d2be399da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c46c696ff5f123a482bae81cf9a1b570.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6bce3d91ca23b86d8c6625f2632e437.png)
(Ⅰ)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20e0e3a328e0bb05b3d5bb92f19d37b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/389bc3f29c058067e06e0d0d2be399da.png)
(Ⅱ)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95e75d73dc0d4eed13fc3240249cab75.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/41c187dc9d7b8ede2b9ae8eedf403061.png)
![](https://img.xkw.com/dksih/QBM/2017/5/18/1689618300526592/1690478760534016/STEM/d19005935e944b13ace1547711f3178b.png?resizew=178)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
名校
解题方法
【推荐2】在几何体中,底面
是边长为2的正三角形.
平面
,若
.
平面
;
(2)是否在线段
上存在一点
,使得二面角
的大小为
.若存在,求出
的长度,若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f4c3f9dd5d0343597a7f58a1989b537.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e82b91596a040f78509748dce011ddde.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f6dd051db98c531f9ef18cdfd793f4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bedde879f99aed69d745d5ec8fe62084.png)
(2)是否在线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3507a1f894fac6b554a49b1167965bbb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac1a63ab608517bb10aa036783dfb51f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
【推荐3】如图所示,在三棱锥S-BCD中,平面
平面
,A是线段
上的点,
为等边三角形,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/6/c8a6185f-5c11-4328-9f9d-06c9de228ee4.png?resizew=146)
(1)若
,求证:
;
(2)若直线
与平面
所成角的正弦值为
,求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8dd470cd9dfcde7f7e1762af28bc649c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca67a5b8f69507c8b80379e86f90a8ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/defa5b53043ae802bb1af7d14374406d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/79482c6de6bbd05affc78f9c625e52f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/110ecc0091f3ddc972869a14f7ebd7d8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0145146072252a8813a880648b2ae557.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/6/c8a6185f-5c11-4328-9f9d-06c9de228ee4.png?resizew=146)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc3ffec2558e590c0712e77d7ab27ec5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b287ca176bb1ad5f7cb76c815c2953d.png)
(2)若直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7dea2ae9d515f9ab351ad72306b776ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ef796b46e68fe77b117ff0483d2370c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f00d5ad6666e6d54e0b2cbe89902132.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
您最近一年使用:0次
【推荐1】如图,在四棱锥
中,底面四边形
为矩形,平面
平面
,
,
,
,点
为
的中点.
(1)求证:平面
平面
;
(2)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/e4aa9084b8fe0fe05c4388d1f835587b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83640592853a53872d7af69c0cffc1bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06201e4f55b78d8b30afb257d5a1b16b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8fced2959882ccc7559584d862f8343c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/9/3/d9e4896a-2e55-40c4-8089-991560d8ed99.png?resizew=187)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c59ee2bf800f774652ed30082c0814fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0628681907ac8d7fdb94d8bc1b15feb9.png)
(2)求三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/689fc4d668f396ff4e3fad57ce9f28f6.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
解题方法
【推荐2】已知长方体
中,底面ABCD为正方形,
,
,点
在棱
上,且
.
(1)在棱CD上确定一点E,使得直线
平面
,并写出证明过程;
(2)求证:平面
平面
;
(3)若动点F在正方形ABCD内,且
,请说明点F的轨迹,试求
长度的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92535536bd3c2761724fd058427f95a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/522230546d4b802094e86ceb48c2ba38.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f66fb71b75b63594ebeeeebd1963eed5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4be266d5a7cadc5071c6cd3d9061fdee.png)
(1)在棱CD上确定一点E,使得直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2496ad1a738d10dd97c57b7a58f852b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/263d398159c7433838b714a9a75d61e5.png)
(2)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df00cdf77ed39ca5a0b305861a693142.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/263d398159c7433838b714a9a75d61e5.png)
(3)若动点F在正方形ABCD内,且
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bbc39144b305c67d44410d41053a1d28.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db5108b8028b16489c9a24fbec4704c0.png)
您最近一年使用:0次