题目内容
(2003•安徽)如图所示,一种花边是由如图弧ACB组成的,弧ACB所在圆的半径为5,弦AB=8,则弧形的高CD为( )![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131019105553964337337/SYS201310191055539643373006_ST/images0.png)
A.2
B.
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131019105553964337337/SYS201310191055539643373006_ST/0.png)
C.3
D.
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131019105553964337337/SYS201310191055539643373006_ST/1.png)
【答案】分析:根据垂径定理和勾股定理解答.
解答:
解:如图所示,AB⊥CD,根据垂径定理,BD=
AB=
×8=4.
由于圆的半径为5,根据勾股定理,OD=
=
=3,CD=5-3=2.
故选A.
点评:将圆补充完整,有助于发现各量之间的关系,便于解答.
解答:
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131019105553964337337/SYS201310191055539643373006_DA/images0.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131019105553964337337/SYS201310191055539643373006_DA/0.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131019105553964337337/SYS201310191055539643373006_DA/1.png)
由于圆的半径为5,根据勾股定理,OD=
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131019105553964337337/SYS201310191055539643373006_DA/2.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131019105553964337337/SYS201310191055539643373006_DA/3.png)
故选A.
点评:将圆补充完整,有助于发现各量之间的关系,便于解答.
![](http://thumb2018.1010pic.com/images/loading.gif)
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