What is the equation for the surface area of a sphere?

1 Answer
Sep 18, 2014

What a cool question! Are you planning on wallpapering a giant basketball? Well, the formula is #SA=4pir^2# just in case you want to calculate it!

Wikipedia gives you the formula, as well as additional information.

You could even use that formula to calculate how much the surface area of the moon is! Make sure to follow the order of operations as you go: first, square your radius, then multiply it by #4pi# using a calculator with a stored approximate value for #pi#. Round appropriately, and then label your answer in square units, depending on what unit of length you are using for the radius. (ex: radius is measured in miles, surface area will be square miles)

Example: the radius of the moon is 1 737.4 kilometers. Find the surface area.
Answer: 38 million square kilometers
The moon's surface area is about 14.6 million square miles (38 million square kilometers), which is less than the total surface area of the continent of Asia (17.2 million sq mi or 44.5 million sq km). The moon's mass is 7.35 x 1022 kg, about 1.2 percent of Earth's mass.