How to get angle from point1 to point2 in earth

Question

I've spend much time internet for finding a way to do this. By exist documention I wrote below code, But it does not show correct angle. What's problem?

private double angleFromCoordinate(double lat1, double long1, double lat2,
            double long2) {

        double dLon = (long2 - long1);

        double y = Math.sin(dLon) * Math.cos(lat2);
        double x = Math.cos(lat1) * Math.sin(lat2) - Math.sin(lat1)
                * Math.cos(lat2) * Math.cos(dLon);

        double brng = Math.atan2(y, x);

        brng = Math.toDegrees(brng);

        brng %= 360;
        // brng = 360 - brng;

        return brng;
    }

UPDATED result of below code:

int angle = (int) angleFromCoordinate(36.288024, 59.615656
                    , 39.033659, 48.662504);
angle is '58'

Answer 1

The methods Math.cos and Math.sin take a number of radians for their arguments. You are passing degrees into this method. You need to convert your degrees into radians at the start of the method.

private double angleFromCoordinate(double lat1, double long1, double lat2,
        double long2) {
    double lat1Rad = Math.toRadians(lat1);
    double long1Rad = Math.toRadians(long1);
    double lat2Rad = Math.toRadians(lat2);
    double long2Rad = Math.toRadians(long2);

then use the new variables lat1Rad and so on for the remaining mathematics.