L=12,S1=4π,S2=2π
S=πR^2
R1 = 根号(S1/π）= 根号(4π/π）= 2
R2 = 根号(S2/π）= 根号(2π/π）= 根号2
侧面积S3=πL(R1+R2)=π*12*(2+根号2)=12π(2+根号2)
圆台的面积S=S1+S2+S3=4π+2π+12π(2+根号2)=30π+12π根号2
设圆锥母线X
(X-L)：X = R2：R1
-L：X = -(R1-R2)/R2
X=LR2/(R1-R2)=12根号2/(2-根号2)=12+12根号2