# Course angles and distance between the two points on the orthodrome(great circle)

Calculates the distance between two points of the Earth specified geodesic (geographical) coordinates along the shortest path - the great circle (orthodrome). Calculates the initial and final course angles and azimuth at intermediate points between the two given.

As we mentioned before, in Course angle and the distance between the two points on loxodrome (rhumb line)., if you are traveling the Earth surface from point A to point B, maintaining the same course angle, your current path won't be the shortest distance between these points.

To achieve your target with the shortest path, you have to correct your course angle so your movement's trajectory will be close to the great circle (orthodromy), which will be the shortest distance between these two points. The following calculator calculates the distance between two coordinates, the initial course angle, the final course angle, and the course angles for the intermediate points. The difference between this calculator from the earlier version Distance calculator is that this one uses a quite precise algorithm developed by Polish scientist Thaddeus Vincenty. The calculation error is less than 0.5mm.

Firstly, the inverse position computation was solved - the distance between the two points was calculated, and the initial and final grid azimuths were found. Then the acquired distance was divided into an equal number of segments following a predetermined number of waypoints. For every segment, the common survey computation was solved - the given directional angle found the coordinates of the next point and the previous point's coordinates. For this solution, Vincenty's algorithm was used (It's described here Direct and Inverse Solutions of Geodesics on the Ellipsoid with the application of nested equations, Survey Review, April 1975)

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