yeah i think u r wrong. a geostationary satellite orbits at a height of 35800 odd kilometres, thats not its distance from the Earth's centre of gravity. so if you took 35800 and subtracted the other number then you would've gotten a height less than that of a geostationary orbit.

what i did was take the equation:

r3/T2 = Gm/4π2

we know that T = 24 hours = 86400 seconds

we know that m = mass of Earth = 6×1024 kg

we know that G = 6.67×10-11

manipulate the equation to make:

r = 3√[T2×(Gm/4π2)]

r = 42,297,523.87 m

now with this you find the height:

h = r - rE

h = 42,297,523.87 - (6.373×106) [it was somewhere around that anyway]

h = 35,924,523.87 m

h = 35,924.52 km

h = 3.592×104 km

that's what i did anyways.