A synchronous satellite, which always remains above the same point on a...

[guanotwozero]

Period T = 2??(r³/GM)
M is mass of planet
r = planet radius + altitude
G = 6.67e-11

so, r³ = GM(T/2?)²

r = 20,413,874.8 m

altitude = 17,043,874.8 m

If I've punched in the right numbers...

 

[mastadeadly]

...planet's equator? Mass planet= 6.42e23(kg)
Radius planet= 3.37e6(m)
Period= 88560(s)

How high is the satellite?