题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033645-97755.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033646-19670.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033646-70995.png)
(Ⅰ)求角C的大小;
(Ⅱ)设角
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033646-66750.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033646-97205.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033647-87925.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033647-71009.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033647-23721.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033647-54979.png)
解析
试题分析:(Ⅰ)利用共线向量的坐标运算,二倍角公式,辅助角公式变形求得;(Ⅱ)根据余弦定理及已知条件求出边
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033647-19951.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033648-94789.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033647-54979.png)
试题解析:(Ⅰ)∵
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033648-80601.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033648-55453.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033648-49977.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033648-23191.png)
得
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033649-59610.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033649-11413.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033649-44191.png)
(Ⅱ)方法1:由已知
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033649-43014.png)
根据余弦定理可得:
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033650-97261.png)
(1)、(2)联立解得:
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033650-78108.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033650-84884.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033647-54979.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033650-26001.png)
方法2:
由正弦定理得:
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033650-66867.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033651-69873.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033651-70788.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033651-53706.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033651-59890.png)
又.
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033647-54979.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033650-26001.png)
方法3:由(Ⅰ)知
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033647-54979.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033649-43014.png)
在
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033645-97755.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033651-55154.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033652-22501.png)
又
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033647-54979.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033650-26001.png)
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033635-97467.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033636-31382.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033636-32814.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033636-23149.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033636-97743.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033637-71385.jpg)
(Ⅰ)请计算原棚户区
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033636-31382.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033635-97467.png)
(Ⅱ)因地理条件的限制,边界
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033637-33238.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033637-45055.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033637-40671.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033638-95382.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033638-94423.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033638-21680.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033638-10906.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033623-36608.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033623-88450.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033624-82145.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033624-26302.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033624-22246.jpg)
经过长期观察
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033624-60057.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033624-70158.png)
(Ⅰ)根据以上数据,求出函数
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033624-26302.png)
(Ⅱ)一般情况下,船舶航行时船底离海底的距离为
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033624-18064.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033625-45000.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033614-76812.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033614-83318.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033614-41723.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033614-96044.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033615-80726.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033615-85643.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033615-33947.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033615-91902.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033605-28474.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033605-20155.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033605-98899.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033606-85866.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033606-34521.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033606-15659.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033556-39752.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033557-21007.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033557-68065.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033557-59144.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033557-87712.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033557-13075.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033558-95305.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033558-20802.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033558-88540.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020033558-10081.png)
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