Hello,

I needed to work out the combinations of 15 locations in groups of 3 as explained here:

http://www.ozgrid.com/forum/showthre…2971#post522971

This gives a large number of spherical triangles. Next I need to use the Haversine formula to work out the distances between these coordinates, i.e. the lengths of the sides of each spherical triangle. I think this formula will work:

**3963.0 * arccos[sin(lat1/57.2958) * sin(lat2/57.2958) + cos(lat1/57.2958) * cos(lat2/57.2958) * cos(lon2/57.2958 -lon1/57.2958)]**

This works from the coordinates in decimal degrees directly rather than converting them to radians. Is it possible to use this formula in Excel? Lat1 is E, Long1 is F, Lat2 is G and Long2 is H. I may have to convert the coordinates into radians first and use this formula:

**3963.0 * arccos[sin(lat1) * sin(lat2) + cos(lat1) * cos(lat2) * cos(lon2 - lon1)]**

I'm not sure how these formulas work with north and south latitudes, north is usually written as positive and south as negative but perhaps they need to be written as 180 degrees. For example the south pole would be 0 degrees and the north pole 180 degrees.