Question: what is the formula for the surface area of a cylinder without top?
Answer: Each end is a circle so the surface area of each end is π * r2, where r is the radius of the end. There are two ends so their combinded surface area is 2 π * r2. The surface area of the side is the circumference times the height or 2 π * r * h, where r is the radius and h is the height of the side.