已知一个圆锥的底面半径为3cm，高为4cm，则这个圆锥的侧面积是（ ） A．5πcm 2 B．10πcm 2 C 如图，圆锥的底面半径为3cm，高为4cm，那么这个圆锥的侧面...
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| ∵圆锥的底面半径为3cm，高为4cm， ∴圆锥的母线长为5cm， ∴圆锥的侧面积为π×3×5=15πcm 2 ， 故选C． |
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