On 3/28/07, Jason Handby <jason.handby at corestar.co.uk> wrote: > Using pythagoras will be quicker than sine and cosine :-) It also won't get you the right answer. You need to use a formula to calculate a triangle on a globe rather than on a plane. If you want to see a bunch of scary formulas, see: http://en.wikipedia.org/wiki/Law_of_cosines_%28spherical%29 Otherwise, search for any number of algorithms on the net. Personally, I would approach this by grabbing a PHP or Perl algorithm and then translating that into VB/C#/whatever. -- Matt Warden Cleveland, OH, USA http://mattwarden.com This email proudly and graciously contributes to entropy.