Let r = radius, h = height and l = slant height
Lateral area = rlpi
But l = sqrt(r^2 + h^2)
Lateral area = r sqrt( r^2 + h^2) pi = 20 pi..................(1)
Total area = r sqrt( r^2 + h^2) pi + r^2 pi = 36pi......(2)
Subtract (1) from (2)
r^2 pi = 16 pi
r^2 = 16
r = 4 cm
Put this value in (1) to find h
4sqrt(4^2 + h^2) pi = 20 pi
sqrt(16 + h^2) = 5
Square both sides
16 + h^2 = 25
h^2 = 9
h = 3 cm
Now that we know h and r we can find the volume
V = 1/3 pi r^2 h
= 1/3 pi (4^2)(3)
= 16 pi cm^3 .........( = 50.27 cm^3)
I hope my answer has come to your help. God bless and have a nice day ahead!