BikeInCity.Utils.GeoMath.SphericalEarthProjectedToAPlane C# (CSharp) Метод

        public static int SphericalEarthProjectedToAPlane(double lat1, double lng1, double lat2, double lng2)
        {
            double diflat = lat1 - lat2;
              double diflng = lng1 - lng2;

              double meanLat = (lat1 + lat2) / 2;

              var help = Math.Cos(meanLat) * diflng;
              int d = (int)(R * Math.Sqrt(diflat * diflat + help * help));
              return d;
        }