题目

已知圆锥的侧面积展开图面积是，母线长为，则圆锥的底面圆半径等于_______. 答案：【答案】【解析】所用等量关系为：圆锥的侧面积=底面周长×母线长÷2．设底面半径为R，则底面周长=2Rπ，圆锥的侧面展开图的面积=×2Rπ×10=30π，∴R=3．故答案为3．________! There is a car coming this way.A.Look upB.Look outC.Look atD.Look on