Calculate endpoint given distance, bearing, starting point

Question

I am trying to find the destination point, given a starting point lat/long, bearing & distance. The calculator from this website below gives me the desired results.

Answer 1

Here's some code that achieves what you want to do.

public static GeoLocation FindPointAtDistanceFrom(GeoLocation startPoint, double initialBearingRadians, double distanceKilometres)
{
    const double radiusEarthKilometres = 6371.01;
    var distRatio = distanceKilometres / radiusEarthKilometres;
    var distRatioSine = Math.Sin(distRatio);
    var distRatioCosine = Math.Cos(distRatio);

    var startLatRad = DegreesToRadians(startPoint.Latitude);
    var startLonRad = DegreesToRadians(startPoint.Longitude);

    var startLatCos = Math.Cos(startLatRad);
    var startLatSin = Math.Sin(startLatRad);

    var endLatRads = Math.Asin((startLatSin * distRatioCosine) + (startLatCos * distRatioSine * Math.Cos(initialBearingRadians)));

    var endLonRads = startLonRad
        + Math.Atan2(
            Math.Sin(initialBearingRadians) * distRatioSine * startLatCos,
            distRatioCosine - startLatSin * Math.Sin(endLatRads));

    return new GeoLocation
    {
        Latitude = RadiansToDegrees(endLatRads),
        Longitude = RadiansToDegrees(endLonRads)
    };
}

public struct GeoLocation
{
    public double Latitude { get; set; }
    public double Longitude { get; set; }
}

public static double DegreesToRadians(double degrees)
{
    const double degToRadFactor = Math.PI / 180;
    return degrees * degToRadFactor;
}

public static double RadiansToDegrees(double radians)
{
    const double radToDegFactor = 180 / Math.PI;
    return radians * radToDegFactor;
}