(1)已知
,
,点
在线段
的延长线上,且
,求点
的坐标;
(2)若
是夹角为
的两个单位向量,求:(i)
的值;(ii)函数
的最小值;
(3)请在以下三个结论中任选一个用向量方法 证明.
①余弦定理;②平行四边形的对角线的平方和等于其四边长的平方和;③三角形的三条中线交于一点.
注:如果选择多个结论分别解答,按第一个解答计分.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98b2cc0d2f6d3eee9a33db83e0c0830d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dd8a31b5335186eb1bea5c80cddcfd9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e490ca1cc66be5a2f1677d243fe093db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8e8b95a61af300412fc65f846089028.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58054eff6c328eb401995a81c6e91a54.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d65f84320b2cea4c64a8254bbceb250.png)
(3)请在以下三个结论中任选一个用
①余弦定理;②平行四边形的对角线的平方和等于其四边长的平方和;③三角形的三条中线交于一点.
注:如果选择多个结论分别解答,按第一个解答计分.
更新时间:2024-05-25 01:45:31
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【推荐1】如图,在三棱锥
中,
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![](https://img.xkw.com/dksih/QBM/2022/3/21/2941122068856832/2941970325708800/STEM/d02ee6ed-8ac3-4396-b1e7-06812695d5de.png?resizew=155)
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(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab8a2ca644d9d7cdb4784a4fd28d3904.png)
(2)若
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解题方法
【推荐2】记
的内角
的对边分别为
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24e0c10fb103930eabd5fa18e8f9bb06.png)
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(1)求
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(2)当
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【推荐1】已知O为
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(1)若
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(2)证明:
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(3)若
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(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91a9cb32a25c2a8bb99f75633b4cd5ed.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc2d37c83486f4717c0fa7787fbe2c4c.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5b8b98b2f83279a49e94d9f48c5e6f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7099026716ee1821dd7d9f157dc055f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/681825f985ce6f2d20735d9260a7b54d.png)
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【推荐2】平面内给定三个向量
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【推荐1】在
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(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/71da232ec4e1f0c809c5b0a1c281aa8c.png)
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(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
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【推荐2】如图,在矩形
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(2)若
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