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已知半径为R和r的两个圆相外切,则它的外公切线长为( ) A.R+r B. C....
已知半径为R和r的两个圆相外切,则它的外公切线长为( )
A.R+r
B.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101192551422789776/SYS201311011925514227897009_ST/0.png)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101192551422789776/SYS201311011925514227897009_ST/1.png)
D.2
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101192551422789776/SYS201311011925514227897009_ST/2.png)
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![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101192551422789776/SYS201311011925514227897005_ST/0.png)
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