where R is the radius of the sphere and Pi is the constant 3.1416.
We have the Diameter D: D=10 mi
Then we can find the radius R: R=D/2 R=(10 mi)/2 R=5 mi
Now ww can calculate the surface area: S=4 Pi R^2 S=4 Pi (5 mi)^2 S= 4 Pi (25 mi^2) S= 100 Pi mi^2 This is the exact answer. Replacing Pi by 3.1416 to get an approximate answer: S= 100 (3.1416) mi^2 S= 314.16 mi^2