tolong sama jalannya ya......

d = 20 dm maka r = 10
t = 28 dm

V = π x r2 x t
V = 3,14 x 100 x 28
V = 8792 dm3

Luas permukaan = 2 x π x r x ( t + r )
= 2 x 3,14 x 10 x (28 + 10)
= 62,8 x 38
= 2386.4 dm2

1/4 x V = 1/4 x 8792
= 2196 dm3 = 2196 liter