Math
posted by Tweets .
The surface area of a sphere is given by the formula 4pi r2, where is it's radius. Although the shape of earth is noth exactly spherical, it has an average radius of 3960 miles. Estimate the surface area of earth.

just substitute the value of radius to the equation:
surface area = SA = 4*pi*r^2
SA = 4*3.14*(3960^2)
SA = 1.97 * 10^8 miles^2
hope this helps~ :)