题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011624-85147.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011624-22733.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011624-95281.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011625-87160.png)
A. 6 B. 13 C.
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011625-84323.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011625-48368.png)
答案
解析
解答:解:延长AO交BC于D,
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011625-87198.png)
连接OB,
∵⊙O过B、C,
∴O在BC的垂直平分线上,
∵AB=AC,圆心O在等腰Rt△ABC的内部,
∴AD⊥BC,BD=DC=3,AO平分∠BAC,
∵∠BAC=90°,
∴∠ADB=90°,∠BAD=45°,
∴∠BAD=∠ABD=45°,
∴AD=BD=3,
∴OD=3-1=2,
由勾股定理得:OB=
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011626-64323.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011625-84323.png)
故选C.
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011618-81717.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011618-80159.png)
于点E,则DE的长是 .
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011615-36274.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011611-88166.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011611-74696.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011611-44634.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011612-95909.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011612-74887.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011612-68374.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011606-29790.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011606-44553.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011606-72093.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011607-34394.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011606-72093.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011607-79059.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011607-35357.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011607-79059.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011607-26025.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011608-80949.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011607-26025.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011606-29790.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011608-34609.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011608-65846.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011608-27754.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011600-93818.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011601-16137.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011601-14670.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011601-26485.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011601-97199.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011601-16137.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011602-29978.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108011601-16137.gif)
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