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用半径为30cm,圆心角为120°的扇形围成一个圆锥的侧面,则圆锥的底面半径为(...
用半径为30cm,圆心角为120°的扇形围成一个圆锥的侧面,则圆锥的底面半径为( )
A.10cm
B.30cm
C.45cm
D.300cm
考点分析:
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