题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004023-13411.png)
(1)求A的大小;
(2)若
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004023-16041.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004023-30369.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004023-76497.png)
解析
试题分析:(1)由余弦定理以及已知条件“
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004023-13411.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004024-92006.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004024-96589.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004023-30369.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004023-30369.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004024-60460.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004024-44054.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004024-37270.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004024-65576.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004025-60713.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004025-34901.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004025-56881.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004025-21591.png)
试题解析:(Ⅰ)∵
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004025-30599.png)
由余弦定理得
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004026-46495.png)
故
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004026-65388.png)
(Ⅱ)∵
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004026-21526.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004024-37270.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004026-16019.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004027-15567.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004024-65576.png)
又∵
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004027-65072.png)
故
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004025-34901.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004025-56881.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004027-90835.png)
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004014-96911.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004014-72424.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004015-35286.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004015-97191.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004015-24857.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004015-54030.png)
A.![]() | B.![]() | C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004007-44524.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004007-62234.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004008-54448.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004008-60288.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004008-29816.png)
(1)求ω的值;
(2)在△ABC中,a、b、c分别是A、B、C所对的边,
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004008-37985.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020004009-55898.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020003956-66263.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020003957-46287.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020003957-91083.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020003957-88183.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020003957-88063.png)
(Ⅰ)求角A的大小;
(Ⅱ)若
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020003958-80935.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020003958-21123.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020003958-80573.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020003958-95474.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020003958-28823.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020003951-62492.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020003951-30719.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020003951-33333.png)
A.2 | B.1 | C.1或2 | D.无解 |
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020003945-61257.png)
A.30° | B.45° | C.60° | D.90° |
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