圆柱体 表面积=2*2*3.14*2+3.14*(2+2)*3 或 3*3*3.14*2+(3+3)*3.14*2
=12.56+12.56*3 =56.52+37.68
=50.24 =94.2
2. 8*(3+3)*3.14*25
=48*3.14*25
=3768 dm平方
37.68*0.5
= 18.84
3.底面直径=208 / 2 / 1300=0.08
底面半径=0.04
底面积=2*(0.04*0.04)*3.14+0.08*3.14*1300
=0.01+326.56
=326.57