This is one of those formulas of algebra and geometry that you need to learn. If you know the radius and the height of a vertical cylinder, then its volume is equal to the (base area) times the (height), which, symbolically, are
V = (base area)(height)
Here,
V = πr²· h where πr² is the area of the base (which is a circle of radius r) and h is the height of the cylinder.
