What is the required altitude for geosynchronous satellites above the Earth?

[bfr]

Homework Statement

Using a development similar to Kepler's law of periods for planets orbiting the Sun, find the required altitude of geosynchronous satellites above the earth.

Homework Equations

(R^3)/T^2=(G*M)/(4pi^2)

The Attempt at a Solution

I'm honestly not even sure where to start. The correct answer is supposed to be 3.59*10^7m above the surface.

 

[Kurdt]

Well you know the period and you want to find the radius. Just rearrange the equation and plug the numbers in.