如图,已知
是正三棱柱,D是AC中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/12/ac9fbaeb-9ff4-422f-8c41-1a4a8157dbd3.png?resizew=191)
(1)证明:
∥平面
;
(2)假设
,
,求线段
在侧面
上的射影长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73a9ad711b25c36dae0c2a2cedff9954.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/12/ac9fbaeb-9ff4-422f-8c41-1a4a8157dbd3.png?resizew=191)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a23890e4d53604bf9f1fefa9380967b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4294ffdba16ae69fd03b13959d682aba.png)
(2)假设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6fa8345302e8036af33d4598282144d7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef0402dd5ae3db10281f9f1e11738bcb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b470c4e195cf7a07b7a331ce4b436e03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f96c673a2381f118ea2d3efc0bca1f3.png)
更新时间:2022-11-09 12:24:31
|
相似题推荐
解答题-证明题
|
适中
(0.65)
【推荐2】如图,四边形
是平行四边形
在平面
上的投影(
),求证:四边形
是平行四边形.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d609847e2ff3d64e5a514582c3ead0e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cae56f784aabab03fb92b848054eb420.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d609847e2ff3d64e5a514582c3ead0e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/23/1fc6c090-23d4-4d51-9031-730f499e8573.png?resizew=183)
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解题方法
【推荐1】如图所示,四棱柱
的侧棱与底面垂直,
交于点
,且
,
分别为
的中点,
,求证:平面
平面![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7935fe3125f247b7bea4f065ce9ad985.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a191f0ff1a17cecee69cb355d79d0744.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.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/9d06f8edd1a1f18ca2dae700c6a29ab4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b753ff3cd2393292221806219bfcd10f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd75a98ab678f06ef8363f9285208ad7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7935fe3125f247b7bea4f065ce9ad985.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/29/30ab1fd4-414f-41de-a2f4-261f4e74cd85.png?resizew=215)
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解答题-问答题
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【推荐2】如图所示,斜三棱柱
中,点
为棱
(不包括端点)上的点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/24/3673b98c-9bc8-4d31-95ea-1c2be221f048.png?resizew=142)
(1)当
等于何值时,
平面
;
(2)设多面体
的体积为
,三棱柱
的体积为
,求
;
(3)若
,
,求异面直线
与
所成角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36cf3bff56a7f4ab6c0008e90823025d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ac99c0358497d72001cc575f1ade329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b10b969819d397711310c8dbb399ebc.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/24/3673b98c-9bc8-4d31-95ea-1c2be221f048.png?resizew=142)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5763b58c5b81fce6257c9792c5ef6b47.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c76388ad7f8db6bb0f37efa9700ed26a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87eeb5402a32ccaaa0be4116e98fb00f.png)
(2)设多面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4f71ab444dbe3c7151181031d77be8ba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81f4784453d5db30fbb7df3ffa85be30.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36cf3bff56a7f4ab6c0008e90823025d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cea87fc8705bde72f090cc253f89b0e4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a21e57b4383c59f2e78bfcec0770fc1c.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/322dea27776098da737428d2f7519cd8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5ab3ca990935ac5a5545398846f6084.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dcca943ee165b1a3ff7e0cc5f463754b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15f73038249a611568193c0bcc286fd7.png)
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名校
【推荐1】《九章算术》中将四个面都是直角三角形的四面体称为“鳖臑”,如图所示,四面体
中,
平面
,
,D是棱
的中点.
![](https://img.xkw.com/dksih/QBM/2021/10/9/2825899502632960/2828633973964800/STEM/1fb582ba-b261-4d8f-af0b-01cb9018f7b7.png?resizew=182)
(1)证明:
.并判断四面体
是否为鳖臑.若是,写出其每个面的直角(只需写出结论);若不是,说明理由;
(2)若四面体
是鳖臑,且
,求二面角
的大小.
![](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/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b10134e7a46e6f6f7cb9d5e2371727d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://img.xkw.com/dksih/QBM/2021/10/9/2825899502632960/2828633973964800/STEM/1fb582ba-b261-4d8f-af0b-01cb9018f7b7.png?resizew=182)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c71dbf267939080668be464f1aa60da.png)
![](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/de2479cd9055e57e504d64ea7d97e71e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b33b7213d99a817bff19bcf740a0697c.png)
您最近一年使用:0次
解答题-证明题
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【推荐2】如图(1)所示
中,
,
.
分别为
中点.将
沿
向平面
上方翻折至图(2)所示的位置,使得
.连接
得到四棱锥
.记
的中点为
,连接
.
平面
;
(2)点
在线段
上且
,连接
,求平面
与平面
的夹角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2205cffebf8c4d5f81d15ed7b85c8936.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d390782b8ea7016628ee68403dcbfbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc1d18e7acbf1db4243914a885261ea0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d240ea67c239b0d9213448c11cba18c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/790ef3382b1c731f2885eecfd92c2a86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36aae82d53f2a35d2f95f467bd5b76cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d9742fb0549cb89e808d50e81bcef49.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19bb1063e139610045f3bca5ca0b2766.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/167d31eb8432b5c0364316e5048c23dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/00c25c4259d935d6e6fabe5c3fc1f43c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e582d73b96ba649378379c3074d506d.png)
(2)点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/167d31eb8432b5c0364316e5048c23dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef77cfa13de39e9ef424e386f84056e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d6592783d1f83c37b051221a7a3a17d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f947fd286e0c37fdcc8d1b6ce4295c7a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
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【推荐3】如图,在三棱柱
中,侧面
为菱形,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/23/aa096d13-7802-4db6-8700-ea3ecbe25e6b.png?resizew=162)
(1)证明:
.
(2)若
,
,
,求平面
与平面
夹角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58cc6184b191e6da43911e701121517e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/00ee347187fbbfe9e8a6faf286795d79.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/23/aa096d13-7802-4db6-8700-ea3ecbe25e6b.png?resizew=162)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7870cee007535b979d35bc7feab75616.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c7fd49bb962841b4575805030e19add.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57e905b1e13fbf8dc6541689968acbe0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3570a95f68349fcd9417fcda62e78e7e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a211ad5a06b505b8365a62c1946f3cb7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99b16cff607cdc2d69afc70dc778acbb.png)
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【推荐1】如图,已知矩形
所在平面与平面
垂直,在直角梯形
中,
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/19/33c99ddc-673e-48e7-8d41-ad78000f6a82.png?resizew=168)
(1)证明:
平面
;
(2)求直线
与平面
所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58cc6184b191e6da43911e701121517e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb55b4b96849ab53b0cb97332801b86d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb55b4b96849ab53b0cb97332801b86d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb5f33fc17da76afec7d7dfcda096e1e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f6e53fed78ccd62a5a9d2f64938a96b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/153e87e7f8396a6f4e57a4e45867c4ae.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/19/33c99ddc-673e-48e7-8d41-ad78000f6a82.png?resizew=168)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a9ee68a3fdc62a86e53d4048e8fc04e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/335187895f612ce811414cfbedf89467.png)
(2)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1cd6a2215f47cdb01078326d245b1523.png)
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解题方法
【推荐2】如图,几何体
中,
,
均为边长为2的正三角形,且平面
平面
,四边形
为正方形.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/19/81cc5422-682d-494f-b2f2-d8204d084499.png?resizew=217)
(1)若平面
平面
,求证:平面
平面
;
(2)若二面角
为
,求直线
与平面
所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/59e89556992cbfd7043330ac7421d342.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1099838f475366002819eb78cbe0e565.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/617edf7f259f5955db7cad814af85281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af6c9a36e2ef7189317ae652c56e49c8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65c42bce098904b241986bb91c65ab33.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/19/81cc5422-682d-494f-b2f2-d8204d084499.png?resizew=217)
(1)若平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce800ada0934832b028ccebb2a81637d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d782bc4aad7cf35baa3de7b8ea73e41f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a09d9d486b7f91ba933210dd013a7f2c.png)
(2)若二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab6d47edbcc2ae6efcfd7f28e401e3e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a8f3a8b0608ec011ad95c522fd2ea4d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9a32bd7a1b78b5a0ec562c4025aea8c.png)
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解答题-证明题
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解题方法
【推荐3】如图,在平行六面体ABCD﹣A1B1C1D1中,底面ABCD为菱形,AC1和BD1相交于点O,E为CC1的中点
![](https://img.xkw.com/dksih/QBM/2022/5/7/2974316549570560/2983258759249920/STEM/0bd4626719cf49a7847396aa9c9d91cb.png?resizew=212)
(1)求证:OE∥平面ABCD;
(2)若平面BDD1B1⊥平面ABCD,求证:D1E=BE.
![](https://img.xkw.com/dksih/QBM/2022/5/7/2974316549570560/2983258759249920/STEM/0bd4626719cf49a7847396aa9c9d91cb.png?resizew=212)
(1)求证:OE∥平面ABCD;
(2)若平面BDD1B1⊥平面ABCD,求证:D1E=BE.
您最近一年使用:0次