23-24高一下·全国·课前预习
1 . 已知向量
,
,
和实数λ,则:
(1)交换律:___________ ;
(2)数乘结合律:_______________ ;
(3)分配律:________________ .
注意:(1)向量的数量积不满足消去律;若
,
,
均为非零向量,且
,但得不到
.
(2)
,因为
,
是数量积,是实数,不是向量,所以
与向量
共线,
与向量
共线,因此,
在一般情况下不成立.
(3)推论:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73a0b19e69be46452425916a0fcb49c9.png)
(1)交换律:
(2)数乘结合律:
(3)分配律:
注意:(1)向量的数量积不满足消去律;若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73a0b19e69be46452425916a0fcb49c9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9dcf295c00ce5def2c8ac6ce4c937e5b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4b7ca4667865ebe617fa6539e8d11fd.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8933b777306573e1f2c4d3dda8f5227d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/854e16eb319ee454088f5b527cf6c4d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c15cd63a9494b3947c9ee121913d9f51.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0795f64078d89a9f5cb3680bce2816b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73a0b19e69be46452425916a0fcb49c9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/380247c556e5174db9ea7e22ccd074b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2b1c174ed96f1dd5043691210f155b5d.png)
(3)推论:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c340671538a445c23040ef2e1a802930.png)
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23-24高一下·全国·课前预习
2 . 已知
,
,则:
(1)![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9e252f76824e2515fa7b951845da789.png)
__________ ,
__________ ,
即两个向量和(差)的坐标分别等于这两个向量相应坐标的和(差).
(2)若点A坐标为
,点B坐标为
,O为坐标原点,
则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/75f051cabd248937ab69fce64a390920.png)
______ ,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d5b06f57b825616050a9b897fb1a50b.png)
________ ,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ee2c8f08a2112767ba279bb135262f5.png)
_________ ,即一个向量的坐标等于表示此向量的有向线段的终点的坐标减去起点的坐标.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c2c857eec21dd64ccf0ba530883bb6cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5bcab0226effeccd2a336c23079bc1be.png)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9e252f76824e2515fa7b951845da789.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65de7c2f24ccd9a5a9b6c5920e981309.png)
即两个向量和(差)的坐标分别等于这两个向量相应坐标的和(差).
(2)若点A坐标为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56720e2f2b0ddd72156da495923698da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2852ae85cfcc804b3192ea8543c88938.png)
则
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/75f051cabd248937ab69fce64a390920.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d5b06f57b825616050a9b897fb1a50b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ee2c8f08a2112767ba279bb135262f5.png)
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23-24高一下·全国·课前预习
3 . 建立平面几何与向量的联系,用_____ 表示问题中涉及的几何元素,将平面几何问题转化为_________
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23-24高一下·全国·课前预习
4 . 用向量方法解决平面几何问题的“三步曲”:
1.建立平面几何与向量的联系,用______ 表示问题中涉及的几何元素,将平面几何问题转化为__________
2.通过__________ ,研究几何元素之间的关系,如距离、夹角等问题.
3.把运算结果“翻译”成几何关系.
1.建立平面几何与向量的联系,用
2.通过
3.把运算结果“翻译”成几何关系.
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23-24高一下·全国·课前预习
5 . 通过_________ ,研究几何元素之间的关系,如距离、夹角等问题.
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23-24高一下·全国·课前预习
6 . 把一个向量分解为_____________ 的向量,叫做把向量正交分解.
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23-24高一下·全国·课前预习
7 . 若与
方向相同的单位向量为
,
与
的夹角为θ,则向量
在向量
上的投影向量为|
|![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aefd06c239145a2b6ae87a955aa51414.png)
.当θ=0时,投影向量为____ ;当θ=
时,投影向量为____ ;当θ=π时,投影向量为______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c984376f5475184e0d3e4f7e1bb65f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aefd06c239145a2b6ae87a955aa51414.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c984376f5475184e0d3e4f7e1bb65f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1ad72d7565699d1ebb741eb0ce12bac.png)
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23-24高一下·全国·课前预习
8 . 已知两个_____ 向量
与
,我们把数量
叫做向量
与
的______ (或____ ),记作
,即
(
为
,
的夹角).
规定:零向量与任一向量的数量积为_____ .
注意:(1)“·”是数量积的运算符号,既不能省略不写,也不能写成“×”;
(2)数量积的结果为数量,不再是向量;
(3)向量数量积的正负由两个向量的夹角
决定:当
是锐角时,数量积为正;当
是钝角时,数量积为负;当
是直角时,数量积等于零.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8947c81bcde38faf61b6a3382fd1fa6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/854e16eb319ee454088f5b527cf6c4d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/210b534709d20121200519821f9be12f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
规定:零向量与任一向量的数量积为
注意:(1)“·”是数量积的运算符号,既不能省略不写,也不能写成“×”;
(2)数量积的结果为数量,不再是向量;
(3)向量数量积的正负由两个向量的夹角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
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23-24高一下·全国·课前预习
9 . 定义:已知两个非零向量
,
,O是平面上的任意一点,作
=
,
=
,则∠AOB=θ(0≤θ≤π)叫做向量
与
的夹角.
注意:①当θ=0时,向量
与![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
_____ ;
时,向量
与![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
_____ ,记作
⊥
;
③当θ=π时,向量
与![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
______ .
注意:只有两个向量的起点重合时所对应的角才是两向量的夹角,如图所示,∠BAC不是向量
与
的夹角.作
=
,则∠BAD才是向量
与
的夹角.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4f605ec0729ce6d72237ad662a06862.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6fc9656d8286c4d6fa309d6ae347c89e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
注意:①当θ=0时,向量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d49f8a63ddbca52039fa9ab44cda6b29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
③当θ=π时,向量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b45ba716f03748c19b7ce2f99af536ab.png)
注意:只有两个向量的起点重合时所对应的角才是两向量的夹角,如图所示,∠BAC不是向量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbaeae7045ad94158cdf5ae97073bc17.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abcb5d89b04570ceda2c29e11cb27a57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/304a7f07db2ec637baadf8f0ab91c85c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbaeae7045ad94158cdf5ae97073bc17.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbaeae7045ad94158cdf5ae97073bc17.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abcb5d89b04570ceda2c29e11cb27a57.png)
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