已知△ABC中,A(2,4),B(-1,-2),C(4,3),BC边上的高为AD.
(1)求证:AB⊥AC;
(2)求点D和向量
的坐标;
(3)设∠ABC=θ,求cos θ.
(1)求证:AB⊥AC;
(2)求点D和向量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/304a7f07db2ec637baadf8f0ab91c85c.png)
(3)设∠ABC=θ,求cos θ.
更新时间:2023-04-03 21:52:08
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【推荐1】如图,在平行四边形ABCD中,点E,F分别在边AB,BC上,且满足
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![](https://img.xkw.com/dksih/QBM/2022/7/1/3013286515974144/3014420357414912/STEM/854bb934854c433a9acaebcda38c3f56.png?resizew=220)
(1)用
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(1)用
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a92e6eba8dab638fd66831cd3a0b6d7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/427fa45527d0ce469bfd060bf6f991f3.png)
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(2)若
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【推荐2】已知
当
为何值时,
(1)
与
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(1)
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(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cfd0f75a47e294603ffa1437fbc501e8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9cd8bbf47b69bbd7a6263b041290d11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c02b54dc6b3e1bb6544f47d4c8743fcf.png)
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解题方法
【推荐1】已知向量
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(1)求
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81f4dcf415977dea53f52a85b6b82136.png)
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(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93af88a7628c71d642d3a6df067c15f5.png)
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(2)当
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【推荐2】如图,已知
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(3)求
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解题方法
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