Circles and PiCylinder Surface

To find the surface area of a cylinder, we have to “unroll” it into its flat net. You can try this yourself, for example by peeling off the label on a can of food.

There are two circlesspheressquares, one at the top and one at the bottom of the cylinder. The curved side is actually a large rectanglesquareellipse.

• The two circles each have area .
• The height of the rectangle is and the width of the rectangle is the same as the circumferencediametertangent of the circles: .