If you are solving a word problem, the radius may be given. The diameter also might be given, which is the distance from one side of the circle to the other, passing through the center point. The radius is exactly one half the diameter. You can measure the radius with a ruler if you are looking for the surface area of an actual cylinder.
To find the area of the base, just plug the radius, 3 centimeter (1. 2 in), into the equation for finding the area of a circle: A = πr2. Here’s how you do it: A = πr2 A = π x 32 A = π x 9 = 28. 26 cm2
