figuring distance from Lat/lon
c 172guy: My Garmin GPS will compute the Great Circle distance for me after I enter the lat and long for each point. Maybe yours will also. Check the owners manual for instructions.
If you have to do it the hard way, "Dutton" gives the Haversine Formula as:
hav dist = (hav DLo)(cos L1)(cos L2)+ hav(L1-L2)
DLo is the difference in longitude and L1-L2 is the difference in latitudes.
If you don''t have Haversine Tables, substitute
(1-cosX)/2 for hav X
Have Fun, George