题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063240-44423.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063240-78128.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-73249.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063240-44423.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-12117.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-92316.gif)
(1)求
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-48716.gif)
(2)若△ABC的面积为sinC,求角C的度数.
答案
(2) C=60°
解析
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-12117.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-83331.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-17482.gif)
得
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-65156.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-17482.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-91220.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063242-29615.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-17482.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063242-74473.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-17482.gif)
(2)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063242-18210.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-17482.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063242-93552.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063243-90739.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063243-85157.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063243-44380.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-17482.gif)
由余弦定理
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063243-95913.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063243-90739.gif)
=
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063243-56017.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-17482.gif)
所以C=60°.
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063241-17482.gif)
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063233-20745.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063233-88408.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063234-63654.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063234-79209.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063234-17399.gif)
A.![]() | B.![]() |
C.![]() | D.![]() ![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063229-47036.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063229-46868.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063229-59654.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063230-71910.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063230-77002.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063230-42590.gif)
在
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063222-17494.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063223-51051.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063223-22040.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063223-98697.gif)
(Ⅰ)若
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063222-17494.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063223-44138.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063224-59989.gif)
(Ⅱ)若
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063224-51788.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063222-17494.gif)
A.60° | B.135° | C.120° | D.90° |
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063214-47802.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063214-60902.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020063214-25587.gif)
A.![]() | B.![]() | C.![]() | D.![]() |
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