如图1,在直角梯形ABCD中,
,
,且
,现以AD为一边向梯形外作正方形ADEF,然后沿边AD将正方形ADEF翻折,使
,M为ED的中点,如图2.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/3/a79dd867-e81b-4a2d-9694-7496a0f02b80.png?resizew=511)
(1)求证:平面
平面BDE;
(2)若
,求D到平面BEC的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f79863ffcfa63117ca6741b20a48e69.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1134c8e3440abb6cd385af2c169037fe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0046177466c78f08d45449dc5639bf38.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3da6e90f9c9617cd495abb57ab9b0e0.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/3/a79dd867-e81b-4a2d-9694-7496a0f02b80.png?resizew=511)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c309e58bf083bad13abd549720a63a22.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82773737609e65dea3c5c67099f1b10d.png)
更新时间:2021-11-19 16:08:41
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相似题推荐
解答题-问答题
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适中
(0.65)
名校
【推荐1】如图,四边形
为梯形,
,
,
,点
在线段
上,且
.现将
沿
翻折到
的位置,使得
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/31/56d16abf-cf10-45ae-8796-f64beadfceb0.jpg?resizew=204)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/31/9f4bd5ef-8cc1-46db-b9ad-9431430c2d94.jpg?resizew=178)
(1)取
中点为
中点为
,证明:
平面
;
(2)证明:
;
(3)点
是线段
上的一点(不包含端点),是否存在点
,使得二面角
的余弦值为
?若存在,则求出
;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0fff774b4b0087a6f304ce930d359be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/998329f9cdb86f5d60d7d5d70fc3781e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86752e4373797b2231f76b074cbf75d0.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/9b937442ad4cc480adc11bb143559454.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dbe40405cd7bd60d69dd535d6da85c00.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c683854275c24b788787f903f9e71da9.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/31/56d16abf-cf10-45ae-8796-f64beadfceb0.jpg?resizew=204)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/31/9f4bd5ef-8cc1-46db-b9ad-9431430c2d94.jpg?resizew=178)
(1)取
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/70ae655bb633041182c9406e6f4eef8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1399e7ae0b2decaafc62a5cdffb15522.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e079b532bed7f57b2e63529fe5043782.png)
(2)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbfbaf73297240eb116f22489519895a.png)
(3)点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc5adb5eb60ae4435a12d93854066298.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98553247801c03de24cf7e687016e655.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d4389367689fb5e0e4fa6f1dc9a5568.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad0d6d600e2676abc87e05cde8aebc1a.png)
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解答题-问答题
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解题方法
【推荐2】如图,四棱锥
的底面
是边长为6的正方形,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/28/13c20716-4b9d-46b2-bf7b-9294b39e4f50.jpg?resizew=181)
(1)证明:
;
(2)当四棱锥
体积为
时,求二面角
的正弦值.
![](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/853cf489108a0c0104d3c3b1fa04cf86.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/28/13c20716-4b9d-46b2-bf7b-9294b39e4f50.jpg?resizew=181)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0921a2db64d89d1d27d4228c4a438a42.png)
(2)当四棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ecedd7dc017ca9cf496e4a7181cb8641.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b33b7213d99a817bff19bcf740a0697c.png)
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解题方法
【推荐1】如图,四棱锥
的底面
为正方形,
,E为PB的中点,已知
,
.
(1)证明:
平面
;
(2)求点C到平面
的距离;
(3)若平面
平面
,求直线EC与平面
所成角的正弦值.
![](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/62974d34de3a12418d6b700420afd1b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fbb3f12377f05ac1d56b95086df09ea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c924c224fac40c01fd9364a7ccaff1.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/5/26/eb749f54-eae5-4405-911c-5ff7f3bb1205.png?resizew=169)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/826bf6fa3706921b77ad0eb4fcc206bd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca48c18021e7be4bbb3e95576e1c1b5f.png)
(2)求点C到平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/852aabd89edffc1b94344ff3f1f31ccd.png)
(3)若平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93edc7bb513f40a89173121c8570cd65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80f747eb5b2d21c9de962cbfd4ec4bb7.png)
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【推荐2】《九章算术》中,将四个面都是直角三角形的四面体叫做“鳖臑”,如图所示,四面体
中,
平面
是棱
的中点,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/14/7cb71401-0dc8-4ea4-9da3-f11c560887ca.png?resizew=148)
(1)判断四面体
是否为鳖臑.若是,请写出每个面的直角(只需写出结论);若不是,请说明理由.
(2)若四面体
是鳖臑,求二面角
的大小;
(3)若
,求点
到平面
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a351136b18bc7d3bd5122332772ab23b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd4fd4b7a4d6b8ca0c5827c055a9ce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50b13c6f183014d6ab494637f3eb71ea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de2479cd9055e57e504d64ea7d97e71e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/14/7cb71401-0dc8-4ea4-9da3-f11c560887ca.png?resizew=148)
(1)判断四面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8922620e649f55d79118cbabf947a8fa.png)
(2)若四面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a351136b18bc7d3bd5122332772ab23b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5a2fd95dfda3f70bc2d9fcd8380bf99.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84d81d732204a3c2384a27606f858677.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b60870baa5e3fbc33a749aa5f0a94be.png)
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解题方法
【推荐1】如图,在直三棱柱
中,
,
,
分别为
的中点.
(1)求EF与
所成角的大小;
(2)求直线
到平面DEF的距离.
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fb717228e1762d335814a3adc90eae45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed10df4140819d5451773a45de66201b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/927456b0989846a2f1573844bbaa2105.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/694c585822f1c159721fd868ef933a31.png)
(1)求EF与
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24bb49fdc6b6bbb2449fdf8a0de769d3.png)
(2)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56f7ba05c54b3de1f4378f7c8eb58328.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/20/2082e79a-690c-4b6f-8c65-84f3c75f816c.png?resizew=175)
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解题方法
【推荐2】如图,在四棱锥
中,四边形
为梯形,
,
,
为等边三角形,
.
![](https://img.xkw.com/dksih/QBM/2017/9/6/1768138570973184/1768171455758336/STEM/49fb4d093c32405e8d69540bfa5e61a9.png?resizew=177)
(1)求证:平面
平面
;
(2)求二面角
大小的余弦值.
![](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/8a11029ca6b4b9e7f777af0280cf163c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e53d55ba51bc5305241144b6cdebc8b7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55a675310c8ba418e5a59beb7317e21e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b07e317ffe7859e81b42ef4970e344a.png)
![](https://img.xkw.com/dksih/QBM/2017/9/6/1768138570973184/1768171455758336/STEM/49fb4d093c32405e8d69540bfa5e61a9.png?resizew=177)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93edc7bb513f40a89173121c8570cd65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b33b7213d99a817bff19bcf740a0697c.png)
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解题方法
【推荐1】如图在直三棱柱
中,
,
,M为
的中点,
,平面
平面
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/5/21/f7fe13d3-9d0c-439c-96a0-8d9c9d5016f8.png?resizew=145)
(1)求AB,BC的长度;
(2)求平面
与平面ABC所成锐二面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/45acdbac251ca6b76a166c1242e71df9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cc416a5b8dc234628e7475387888d82.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8dc93ef1a20fcf86ee65e4346712b353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03c5088536dad890222fe47df3de5efb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d9a8181f7a7fe7f3fac872ce9534f15.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/5/21/f7fe13d3-9d0c-439c-96a0-8d9c9d5016f8.png?resizew=145)
(1)求AB,BC的长度;
(2)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46b91c857bbe3c4f0f08dd2a4124a96e.png)
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【推荐2】如图,三角形
所在的平面与长方形
所在的平面垂直,
,
,
.点
是
边的中点,点
分别在线段
上,且
,
.
(1)证明:
;
(2)求直线
与直线
所成角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/218054144a13435580cd132b9459546c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c219d61264775f02bc18ca0276a9238.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/305a88d4e0249bd16d48eda01331d2d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f8eeeea1c9652cacce976f8129cf520.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/c741cf8348e9fa4ee6894ac2c3ac6dad.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3355e2fa0ac6c675f02ee36c3ced4f2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84f31a3724c639f88486f8356ca65397.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0add97c20dbfc86bcfa651b21356fc1.png)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e3866b1582f16c44f50f9f97c274f9e.png)
(2)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd33764ff4efddfe11a98a609753715c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c63e36329f5e0979f5ee776ac5d06327.png)
![](https://img.xkw.com/dksih/QBM/2017/11/22/1822564645511168/1825760485826560/STEM/3b5f5d05f8cf4c5dbe1e2790a13a7059.png?resizew=173)
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【推荐3】已知空间几何体
,底面
为菱形,
,
,
,
,
,平面
平面
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/20/674388af-43e4-4267-9955-7919d1e0391e.png?resizew=178)
(1)求证:
;
(2)若直线
与平面
所成角为
,求直线
与平面
所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9165d9bfbb0f0d19eb482c2a4c1b29b7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42ebdf20b0af9cadf88f5d6d3e5c62c8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e41d3f7d55fcbaebc4e2450ac63a3dc5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38d00572a90232e08932317af2a53767.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/634e116ca7402e925c9af92a64045053.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23740391715f0f7b8b82d3393d3c0ca8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d28c625d7ac6878957facc8274d459c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97f10d697dd9c980a043a62732254d02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82d04de2a2c49e48f3a28e68919e1693.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/20/674388af-43e4-4267-9955-7919d1e0391e.png?resizew=178)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d055205e9a6387a3f6f9439650d5306.png)
(2)若直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f05f69e0911b75324f77488a178995c4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a09d9d486b7f91ba933210dd013a7f2c.png)
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