A satellite which revalues around the earth in its equatorial plane with the same angular speed and in the same direction as the earth rotates about its own axis is called a geostationary or synchronous satellite.
The height of a satellite above the earth's surface is given by
$h=\left(\frac{T^2R^2g}{4\pi^2}\right)^{1/3} -R$
But T = 24 h = 86400 s
R = radius of earth = 6400 km
$g=9.8 ms^{-2}=0.0098 kms^{-2}$
= $h=\left(\frac{(86400)^2\times(6400)^2\times0.0098}{4\times9.87}\right)^{1/3}$
d = 42330 - 6400 = 35930 km
= 36000 km