using System;

public static class Program

{

    static double toRadians(double angle)

    {

        return (angle * Math.PI) / 180;

    }

​

    static double CalcDistance(double lon1, double lon2, double lat1, double lat2)

    {

        lon1 = toRadians(lon1);

        lon2 = toRadians(lon2);

        lat1 = toRadians(lat1);

        lat2 = toRadians(lat2);

        //haversine formula

        double dlat, dlon;

        dlat = lat2 - lat1;

        dlon = lon2 - lon1;

        double a = Math.Pow(Math.Sin(dlat / 2), 2) +

            Math.Cos(lat1) * Math.Cos(lat2) *

            Math.Pow(Math.Sin(dlon / 2), 2);

        double c = 2 * Math.Asin(Math.Sqrt(a));

        // earths radius is KM, use 3956 for miles

        double earthRadius = 6371;

        return (c * earthRadius);

    }

​

​

​

    static void Main(String[] args)

    {

        double lat1, lat2, lon1, lon2;

        lon1= 53.222469;

        lat1 = -4.129424;

        lon2 = 53.244697;

        lat2 = -2.13195;

        Console.WriteLine(CalcDistance(lon1, lon2, lat1, lat2) + " KM");

    }

}