SOLUTION: find the surface area of a cylinder whose bases are circle with a radius of 18 inches and the height of the cylinder is 48 inches

Algebra ->  Surface-area -> SOLUTION: find the surface area of a cylinder whose bases are circle with a radius of 18 inches and the height of the cylinder is 48 inches      Log On


   

Question 698706: find the surface area of a cylinder whose bases are circle with a radius of 18 inches and the height of the cylinder is 48 inches
Answer by Positive_EV(69) About Me  (Show Source):
You can put this solution on YOUR website!
The surface area of a cylinder is equal to the sum of the areas of the circles on the top and bottom of the cylinder and the area around the cylinder.

The area of a circle is pi%2Ar%5E2, where r = 18, so pi%2A18%5E2+=+324%2Api is the area of each circle.

The area of the section between the circles is a bit trickier. You can think of this section as a rectangle rolled up into a cylindrical shape. This rectangle has a height of 48, and a width equal to the circumference of the circle, which is

2%2Api%2Ar+=+2%2Api%2A18+=+36%2Api.

The area of this rectangle is equal to the height times the width, which is 48%2A%2836%2Api%29+=+1728%2Api.

The sum of the area of the three parts is 324%2Api+%2B+324%2Api+%2B+1728%2Api+=+2376%2Api.

The surface area is 2376*pi = 7464.424 square inches.