A satellite is to be placed in equatorial geostationary orbit around earth for communication.

(a) Calculate height of such a satellite.

(b) Find out the minimum number of satellites that are needed to cover entire earth so that at least one satellites is visible from any point on the equator.

[M = 6 x 10^{24} kg, R = 6400 km, T = 24h, G = 6.67 x 10^{-11} SI units]