4. Great Circle Distance

Figures from Welcome to the Universe, Neil deGrasse Tyson, Michael A. Strauss & J. Richard Gott, 2016, Chapter 19:

triangle with three right angles

great circle distance from New York to Tokyo

Earth Rectangular Coordinates

Earth Spherical Coordinates

chapter4_4.c - great circle distance -> using Point structure

...
   printf("Great Circle Distance: %.0f miles \n",
           gc_distance(lat1,long1,lat2,long2));
...
double gc_distance(double lat1, double long1,
                   double lat2, double long2)
{
   ...

   return gamma*rho;
}

Test input latitude and longitude:

New York = 40.75 N, 74 W

London = 51.5 N, 0 W

Distance should be 3466 miles.