Question

Earth's equator is about 24,902 mi long. What is the approximate surface area of Earth?

Answer 1

197 million square miles

Explanation:

Remark

What the equator is telling you is that the circumference around the earth is approximately 24902 miles. So before you can find the surface area, you need to find the radius of that circumference.

Equations

C = 2*pi*r

Area = 4pi*r^2

Solution

Radius

C = 24902

pi = 3.14

r = ?

24902 = 2 * pi * r

r = 24902 / (2 * pi)

r = 3965.29

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Surface Area

Area = 4 * pi * r^2

Area = 4 * 3.14 * 3965.29^2

Area = 4 * 3.14 * 15,723,498

Area = 197 000 000 square miles