题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071450-36595.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071450-39901.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071450-37842.gif)
(1)若
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071451-40417.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071451-13061.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071451-86361.gif)
(2)若
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071451-28955.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071452-62242.gif)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071452-88596.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071451-40417.gif)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071452-15162.gif)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071452-58806.gif)
又
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071450-39901.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071450-37842.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071453-35120.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071453-84534.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071453-24777.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071453-74221.gif)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071453-98304.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071454-69207.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071454-11812.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071454-58321.gif)
(2)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071454-87976.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071455-20380.gif)
由
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071455-98746.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071455-69235.gif)
可得
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071455-28873.gif)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071455-45086.gif)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071456-59914.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071456-36213.gif)
解析
核心考点
试题【.(本小题满分12分)已知平面上三点,,.(1)若(O为坐标原点),求向量与夹角的大小;(2)若,求的值.】;主要考察你对平面向量数量积的意义等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071443-72534.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071444-29548.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071444-28167.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071444-39952.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071439-47648.gif)
A.4 | B.3 | C.2 | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071434-66994.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071435-27049.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071435-70355.gif)
A.36 | B.12 | C.6 | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071430-18166.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071430-50213.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071430-36867.gif)
A.0 | B.3 | C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071421-48893.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071421-73264.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071422-21147.gif)
(1)证明;
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071422-43157.gif)
(2)当
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071422-52913.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104071422-91663.gif)
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