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 ???

, one at the top and one at the bottom of the cylinder. The curved side is actually a large ???

squarerectangleellipse

.

• The two circles each have area
  ​
  +

  ×

  π
  .
• The height of the rectangle is
  ​
  and the width of the rectangle is the same as the ???
  circumferencediametertangent
  of the circles:
  ​
  +

  ×

  π
  .