题目内容
如图,AB为⊙O的弦,AB=8,OC⊥AB于点D,交⊙O于点C,且CD=l,求⊙O的半径.
![](http://thumb.1010pic.com/pic2/upload/papers/20140826/201408260112474773609.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140826/201408260112474773609.png)
如图:
连接OA,由OC⊥AB于D,得:AD=DB=
AB=4.
设⊙O的半径为r,在Rt△OAD中,OA2=AD2+OD2
∴r2=(r-1)2+42
整理得:2r=17
∴r=
.
所以圆的半径是
.
![](http://thumb.1010pic.com/pic2/upload/papers/20140826/201408260112475554049.png)
连接OA,由OC⊥AB于D,得:AD=DB=
1 |
2 |
设⊙O的半径为r,在Rt△OAD中,OA2=AD2+OD2
∴r2=(r-1)2+42
整理得:2r=17
∴r=
17 |
2 |
所以圆的半径是
17 |
2 |
![](http://thumb.1010pic.com/pic2/upload/papers/20140826/201408260112475554049.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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