Eu tenho 3 maneiras de calcular a distância e todas as 3 me dão respostas diferentes,

    double lat = 6.924049;
    double lng = 79.853807;

    double lat1 = 6.856461;
    double lng1 = 79.912748;

Como calcular a distância entre dois pontos e como calcular o percentual em Km? ou metros?

1a via ans = 9,967441199417708E-6

float[] results = new float[1];
Location.distanceBetween(lat / 1E6, lng / 1E6, lat1 / 1E6, lng1 / 1E6,results);
float s =results[0] * 0.000621371192f;
String a2 = Float.toString(s);

Ò caminho ans = 6,1795527E6

double lat3 = lat / 1E6;
double lat2 = lat1 / 1E6;
double lon3 = lng / 1E6;
double lon2 = lng1 / 1E6;
double dLat = Math.toRadians(lat2 - lat3);
double dLon = Math.toRadians(lon2 - lon3);
double a = Math.sin(dLat / 2) * Math.sin(dLat / 2) +
Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) *
Math.sin(dLon / 2) * Math.sin(dLon / 2);
double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
// 6378.1 is gravity of earth
double asd = c * 6378.1;

3a via ans = 6,176576174444191

{
double a5 = distance(lat, lng, lat1, lng1);
String a6 = Double.toString(a5);
}
private double distance(double lat1, double lon1, double lat2, double lon2) {
        double theta = lon1 - lon2;
        double dist = Math.sin(deg2rad(lat1)) * Math.sin(deg2rad(lat2))
                + Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2))
                * Math.cos(deg2rad(theta));
        dist = Math.acos(dist);
        dist = rad2deg(dist);
        dist = dist * 60 * 1.1515;
        return (dist);
    }

    private double deg2rad(double deg) {
        return (deg * Math.PI / 180.0);
    }

    private double rad2deg(double rad) {
        return (rad * 180.0 / Math.PI);
    }

Então, como calcular a distância entre dois pontos e como a porcentagem no KM? ou metros?