题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062110-89827.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062110-30226.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062110-42478.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062110-20791.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062111-59954.png)
(1)求角
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062111-72603.png)
(2)求
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062112-88373.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062112-32219.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062112-47948.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062112-22936.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062113-80568.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062113-55578.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062113-54322.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062114-83895.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062114-85110.png)
又
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062114-76145.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062115-51125.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062115-15840.png)
第一问:另解: ∵
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062115-83888.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062115-45782.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062112-22936.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062116-13860.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062116-74266.png)
(2)由(1)可知
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062116-32224.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062116-52872.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062117-91228.png)
∵
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062117-91263.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062117-16407.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062113-80568.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062118-40422.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062118-56822.png)
解析
核心考点
试题【已知向量,且与向量的夹角为,其中是的内角. (1)求角的大小; (2)求的取值范围.】;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/20191104/20191104062103-29798.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062103-89101.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062103-62684.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062103-60053.png)
A.![]() | B.1 | C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062055-19233.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062055-55875.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062055-20860.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062055-21096.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062056-65034.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062056-42370.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062056-39807.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062050-91008.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062050-17256.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062050-60570.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062051-55927.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062051-24884.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062051-90323.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062043-96329.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062044-66801.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062044-67031.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062044-39887.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104062045-15698.png)
A.1 | B.7 | C.-10 | D.-9 |
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