How to calculate the radians between two coordinate points on the sphere of the earth

How to calculate the radians between two coordinate points on the sphere of the earth

First, check that you have read the following articles by the blogger:

[Google
Map: calculate the distance between two points based on the dimension, and calculate the latitude and longitude of the target location based on the latitude and longitude.

Http://blog.csdn.net/ghlfllz/article/details/6097637

[Google
Map: how to obtain a Square area based on the coordinate origin (longitude and latitude) and distance Value

Http://blog.csdn.net/ghlfllz/article/details/6097749

Based on the descriptions in the previous two articles, calculate the distance between the two coordinates, in meters,

Generally, the earth's equator radius is 6378137 meters, the Earth's polar radius is 6356725 meters, and the Earth's average radius is 6371004 meters.

We know that the Radian of a circle is 2pai, and the formula for calculating the circumference of the circle is: circumference = 2pai * radius,
It can be inferred that the radian formula is: radian = radius/perimeter

Therefore, the radian distance between two coordinate points is: distance (meter)/6371004.