设圆柱的底面半径为R,则有两个底的面积和为:π R²*2=2π R²;
侧面积为:2πR*15=30πR.
故:2π R²+30πR=200π;
R²+15R-100=0;
(R+20)(R-5)=0;
R=-20或5.(R=-20,舍去)
故底面半径为5厘米.
设圆柱的底面半径为R,则有两个底的面积和为:π R²*2=2π R²;
侧面积为:2πR*15=30πR.
故:2π R²+30πR=200π;
R²+15R-100=0;
(R+20)(R-5)=0;
R=-20或5.(R=-20,舍去)
故底面半径为5厘米.