题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042553-14251.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042553-72053.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042553-95513.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042553-72998.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042554-88946.png)
(1)求角
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042554-90261.png)
(2)若
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042553-14251.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042554-50812.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042554-32148.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042554-52403.png)
解析
试题分析:1)因为
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042553-72998.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042555-58038.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042555-64782.png)
因为
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042555-11415.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042555-67875.png)
因为
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042556-22951.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042554-32148.png)
2)(因为
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042556-32536.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042556-74512.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042556-37779.png)
由余弦定理得:
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042556-71021.png)
因为
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042554-32148.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042557-75495.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042557-69166.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042554-52403.png)
点评:典型题,本题较全面地考查三角知识内容。研究三角形问题,要注意挖掘运用三角形中的“隐含条件”。(2)中由“
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042553-14251.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042554-50812.png)
核心考点
举一反三
如图所示,在一个特定时段内,以点E为中心的10海里以内海域被设为警戒水域.点E正北40
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042546-98587.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042546-98587.png)
(1)求该船的行驶速度(单位:海里/小时);
(2)若该船不改变航行方向继续行驶.判断它是否会进入警戒水域,并说明理由.
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042542-62331.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042542-57356.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042543-84791.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042543-24691.png)
则角A的大小是__________.
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042534-33633.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042534-73193.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042534-56336.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042534-60099.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042535-62122.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042535-25384.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042535-33831.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042535-85707.png)
(I)求角
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042534-56336.png)
(Ⅱ)若
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042535-42043.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042536-68075.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042527-66395.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042527-69932.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042527-40776.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042527-88621.png)
A.13 | B.![]() | C. 7 | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020042519-20176.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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