# Spherical Coordinates: Distance Between 2 Points

1. Mar 16, 2014

### jsbxd9

Hello,

I am looking into finding geodesic distances for an ellipsoid. I will designate two points then find the distance between them. This will be my geodesic distance. I have put together a schematic (attached) for reference. Ultimately I need to know the distance D as shown on the attachment. I figured if I found β I could use the law of cosines to figure the distance D. I have also been reading a book that states D = √(ρ12 + ρ22 - 2ρ1ρ2 (cosθ1cosθ2 + cos (ø1 - ø2) sinθ1 sinθ2)) I cannot figure out the way this equation was derived so I am not sure if it will work.

Please let me know if you have a solution.

Thank you,
- Jonathan

View attachment Spherical Coordinate System.pdf

Last edited: Mar 16, 2014