The synchronous communication satellite must be above the equator of the earth, so we can consider making a right triangle with the position of the satellite, the position of Beijing and the corresponding point of the satellite on the equator. Solve it. The starting point plane is the equatorial plane and the straight line is the local ground normal. The so-called normal is a straight line perpendicular to the reference oblate sphere. The latitude of a place is the angle between the normal and the equatorial plane. Latitude is measured on the local meridian, from the equator to the north, the northern value is called north latitude, and the southern value is called south latitude. It can be seen that the latitude of a place is its direction and angular distance from the equator. The equator is latitude 0, and the maximum north latitude is 90, which is the North Pole. The maximum south latitude is 90, which is the South Pole.