Thus the centrifugal force experienced by this satellite is
where 
is the mass of the satellite.
The gravitiaional force experienced by the satellite is given by
Here 
is the gravitational constastant,
and 
is the mass of the earth.
For a stable circular orbit, the centrifugal force, which is directed outward radially must balance the gravitational force, which is directed inwardly. With simple algebra we can thus derive an expression relating the radius r and the period T of any satelite orbiting the Earth.
For a geosynchronous orbit we have
, giving
The altitude of the satelite is r minus the radius of Earth (6370 km), which is 35,880 kilometers.