A是
所在平面外一点,G是
的重心,M、E分别是BD、AG的中点,点F在线段AM上,
,判断三点C、E、F是否共线.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/661ff55b5ebbadfb600989af3cfce2fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/661ff55b5ebbadfb600989af3cfce2fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf5a04db3574bcdda2333ec29450269d.png)
21-22高二·全国·课后作业 查看更多[3]
沪教版(2020) 选修第一册 单元训练 第3章 空间向量及其运算、空间向量基本定理(B卷)(已下线)专题1.3 空间向量基本定理【八大题型】-2023-2024学年高二数学举一反三系列(人教A版2019选择性必修第一册)(已下线)第七章 应用空间向量解立体几何问题拓展 专题一 空间向量基底法 微点1 空间向量基底法(一)【基础版】
更新时间:2022-05-05 19:39:55
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解答题-证明题
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【推荐1】如图,四边形ABCD和ABEF都是平行四边形,且不共面,M,N分别是AC,BF的中点,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/896aed45bd3b045b66a8fa93641546b9.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/8/268220b5-fe7f-4b2e-8562-8a354a7d2b41.png?resizew=161)
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【推荐2】四棱柱
的六个面都是平行四边形,点
在对角线
上,且
,点
在对角线
上,且
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/6/4d6704cd-d846-48a0-8dfc-3b921517bb0e.png?resizew=185)
(1)设向量
,
,
,用
、
、
表示向量
、
;
(2)求证:
、
、
三点共线.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3da8c338342e38c9aa3f274c053fd5b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e663220a66eff19da6a71e46b397db2e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7edc594bc197a4f8ae571df31d22b56.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6eb97aff0960e2640314888a38e7169c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ae4af331bca6587521e6dd4212f78d1.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/6/4d6704cd-d846-48a0-8dfc-3b921517bb0e.png?resizew=185)
(1)设向量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7b9d8a08fc52c31cc1a7f527d18b55c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/184359fe3cadc363cf4ebe586c2b3db4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/39b0ff98fe5e0a913ebecda552acc6f6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a2f4b1178f68bd147d1a2a6acd04435.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c94075193c11fe43f2396cff5a485054.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d366d8fbb7258ee051f49977441e14a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c7ef300fccd1d15cfd5556f9d742e12f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a53766326ff2736199a9318970f1603c.png)
(2)求证:
![](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/e5b3bd5e6bc2a0a277d279bb01af9584.png)
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解题方法
【推荐1】已知正三棱锥P-ABC的所有棱长均为
,点E,F分别为PA,BC的中点,点N在EF上,且
,设
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/16/7a9891cc-d3ae-4971-9449-95e37ffd1967.png?resizew=151)
(1)用向量
表示向量
;
(2)求PN与EB夹角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e4b5a2ccac15d3015249bd19a1876f1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0d91f0d4a64f599976effc1730cefdc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ae7dc09ab4960c7e8df32c39a573448.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/16/7a9891cc-d3ae-4971-9449-95e37ffd1967.png?resizew=151)
(1)用向量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e12e95f703ad30ab9a3d38376830989.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea2e331e5e22fdb7a057526934384c41.png)
(2)求PN与EB夹角的余弦值.
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【推荐2】如图,平行六面体
中,
与
相交于
,设
、
、
,
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/31/639e840d-d661-49bb-b555-e1c88c5b02b5.png?resizew=203)
(1)用
、
、
表示
;
(2)若
、
、
三向量是两两成
角的单位向量,求
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7b9d8a08fc52c31cc1a7f527d18b55c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/184359fe3cadc363cf4ebe586c2b3db4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2410e0e103cc41264a2d0f5c0e3f3ed4.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/31/639e840d-d661-49bb-b555-e1c88c5b02b5.png?resizew=203)
(1)用
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a2f4b1178f68bd147d1a2a6acd04435.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c94075193c11fe43f2396cff5a485054.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d366d8fbb7258ee051f49977441e14a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4e80d96f4bb4963c97c67a30e660da1.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a2f4b1178f68bd147d1a2a6acd04435.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c94075193c11fe43f2396cff5a485054.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d366d8fbb7258ee051f49977441e14a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e5b6a918d3e4db2f4fea50abc44cc29.png)
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