题目
题型:不详难度:来源:
答案
解析
试题分析:过点A做BC的高AD,垂足为D
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100908-45105.png)
sin∠ABC=
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100909-98787.png)
根据勾股定理可得BD=3,又因为△ABC是等腰三角形,所以CD=3
所以,BC=6.
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100853-34238.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100854-23441.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100854-97584.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100854-76884.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100855-64601.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100855-60941.png)
……
观察上述等式,猜想:对任意锐角
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100855-53537.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100855-79863.png)
(1)(3分)如图,在锐角三角形
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100855-93302.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100856-74631.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100856-66756.png)
(3分)已知:
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100856-74631.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100856-39021.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100856-98245.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100857-53184.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100859-71720.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100859-90474.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100859-69694.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100842-57786.png)
A.![]() | B.![]() |
C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100832-58430.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100833-96639.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100833-12647.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100824-54624.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100824-50384.png)
(2)已知
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100824-92384.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100825-14892.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104100825-27470.png)
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