武汉位于东经 114°,北纬 31° ,而北京位于东经116°,北纬 4 0° ,那么 ,武汉和北京的球面距离有多远 ?(以上称问题 )为了解决这个问题 ,先介绍了一个定理 .为方便叙述 ,本文采用有向角 ,规定东经为正 ,西经为负 .北纬为正 ,南纬为负 .例如西经 12 0°记为- 12 0° ,南纬 30° Wuhan is located at longitude 114° east and latitude 31° north, while Beijing is located at 116° east longitude and 40° north latitude. So how far does the spherical distance between Wuhan and Beijing far? (To solve the problem, we first introduce a theorem.) In order to facilitate the description, this paper adopts a directional angle, stipulating that the longitude is positive and the west is negative. The northern latitude is positive and the south latitude is negative. For example, the longitude of 12° is -12°, and the latitude is 30°.