题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060427-59212.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060427-55411.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060428-61243.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060428-16219.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060428-13979.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060428-61243.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060428-61010.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060429-63887.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060429-10067.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060429-57956.png)
解析
(1)因为根据余弦定理变形可知得到角C的余弦值,然后求解得到角的值
(2)结合第一问的结论,得到
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060429-39877.png)
解:(1)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060430-61630.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060430-13990.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060430-76756.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060429-10067.png)
(2)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060429-39877.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060430-27473.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060431-78021.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060431-51453.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060431-77830.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060431-51123.png)
核心考点
试题【(本题满分14分)已知向量,且,其中是的三内角,分别是的对边.(1)求的大小;(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/20191104/20191104060423-94791.png)
A.
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060423-13261.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060424-28859.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060424-30839.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060424-69566.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060417-76051.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060417-39157.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060417-38620.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060418-79637.png)
A.![]() | B.![]() | C.4 | D.12 |
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060411-73085.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060412-86437.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060412-81379.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060412-22284.png)
A.直角三角形 | B.钝角三角形 | C.锐角三角形 | D.以上均有可能 |
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060402-41347.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060402-93770.png)
(1)求向量
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060402-36711.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060402-36711.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060402-17151.png)
(2)若
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060402-15760.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060402-86306.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060403-64984.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104060355-49163.png)
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