题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045126-37564.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045126-47194.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045126-91792.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045127-60336.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045126-47194.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045126-91792.png)
(I)求角A的大小;
(II)若a=2,b=2
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045127-72691.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045126-37564.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045127-85662.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045126-37564.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045127-28270.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045128-48570.png)
解析
试题分析:(I)根据
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045128-29349.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045126-91792.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045128-51449.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045128-88610.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045127-85662.png)
(II)首先由正弦定理可得:
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045129-29651.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045129-25290.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045129-55521.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045129-61890.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045130-86655.png)
根据
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045129-61890.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045130-37865.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045130-67511.png)
进一步确定
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045126-37564.png)
试题解析:(I)因为
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045128-29349.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045126-91792.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045130-69582.png)
因为
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045128-88610.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045127-85662.png)
(II)由正弦定理可得:
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045129-29651.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045129-25290.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045129-55521.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045129-61890.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045130-86655.png)
当
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045129-61890.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045130-21331.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045131-42827.png)
当
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045130-37865.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045131-31432.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045131-46558.png)
故
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045126-37564.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045127-28270.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045128-48570.png)
核心考点
试题【已知a,b,c分别为ABC的三个内角A,B,C的对边,=(sinA,1),=(cosA,),且//.(I)求角A的大小;(II)若a=2,b=2,求ABC的面积】;主要考察你对两角和与差的三角函数等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045053-40919.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045053-75137.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045054-35185.png)
(1)求函数
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045054-36832.png)
(2)在
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045054-45641.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045054-36024.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045055-82114.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045055-52864.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045055-88323.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045054-45641.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045055-85713.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923045019-43201.png)
(Ⅰ)求sinA的值;
(Ⅱ)若△ABC的面积S=12,b=6,求a的值.
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044859-63589.png)
A.![]() | B.![]() | C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044747-24366.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044747-17059.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044747-95633.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044748-98446.png)
(1)求角A;
(2)若
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044748-74226.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044748-84795.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044706-86945.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044706-51033.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044706-46946.png)
(Ⅰ)求
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044707-84945.png)
(Ⅱ)在
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044707-68259.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044707-70102.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044707-28599.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044708-51233.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044708-33332.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044708-99431.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190923/20190923044708-14254.png)
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