degree between two points latitude longitude c#

float DeltaFi = (float)ConvertToRadians(lat2 - lat1);
float DeltaLambda = (float)ConvertToRadians(lon2 - lon1);
float a = Mathf.Sin(DeltaFi / 2) * Mathf.Sin(DeltaFi / 2) + Mathf.Cos(fi1) * Mathf.Cos(fi2) * Mathf.Sin(DeltaLambda / 2) * Mathf.Sin(DeltaLambda / 2);
float c = 2 * Mathf.Atan2(Mathf.Sqrt(a), Mathf.Sqrt(1 - a));
float distance = earthD * c;

float lambda1 = (float)ConvertToRadians(lon1);
float lambda2 = (float)ConvertToRadians(lon2);
float fi1 = (float)ConvertToRadians(lon1);
float fi2 = (float)ConvertToRadians(lon2);

float y = Mathf.Sin(lambda2 - lambda1) * Mathf.Cos(fi2);
float x = Mathf.Cos(fi1) * Mathf.Sin(fi2) - Mathf.Sin(fi1) * Mathf.Cos(fi2) * Mathf.Cos(lambda2 - lambda1);
float degree = (float)ConvertToDegree(Mathf.Atan2(y, x));