(2002•兰州)附加题:已知,等腰△ABC内接⊙O,顶角为120°,⊙O的半径为
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131021232610869407006/SYS201310212326108694070008_ST/0.png)
cm,求底边BC的长.
考点分析:
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的等边三角形ABC内接于⊙O,点D在
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