Calculating the Radius of a Geostationary Orbit

To calculate the radius of a geostationary orbit, the centripetal force must equal the gravitational force on the satellite or mass..

Through the use of re-arranging the above equation, we can come to the equation:

r³ = G (m2) T² / 4π²

We  know that (m2) is the mass of the earth at 5.98×10^24 kg, T is the time period and G the universal gravitation constant at 6.67 x10^-11 kg^-2 .