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如图,点A、B、C在⊙O上,切线CD与OB的延长线交于点D,若∠A=30°,CD...
如图,点A、B、C在⊙O上,切线CD与OB的延长线交于点D,若∠A=30°,CD=2,则⊙O的半径为
.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101190927754281360/SYS201311011909277542813013_ST/images0.png)
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