The time period of revolution of a geostationary satellite around the Earth is

A geostationary satellite stays above the same point on the equator, so its period must equal the Earth's rotation period of about 24 hours, and it orbits in the equatorial plane from west to east at about 36,000 km above the surface. A period of about 90 minutes belongs to a low Earth orbit, and 365 days is the Earth's own orbital period around the Sun.