A cylinder has a radius r and a height h see picture below. You can use these calculations to determine that here. The formula is V pr 2 h where V is the Volume r is the radius of the circular base h is the height and p is the constant pi.
Online calculators and formulas for a cylinder and other geometry problems.
H Height of the cylinder. Cylinder_volume p R² - r² cylinder_height. You can use these calculations to determine that here. R squared times pi times height 12 times 12 times pi times 20 144 times pi times 20 which is around 9048 meters squared.