how to draw Ellipse

[hhfh]

double dist_rad = radius / m_world.EquatorialRadius;
Angle lat_rad = Angle.FromDegrees(0);
Angle lon_rad = Angle.FromDegrees(0);
double dlon_rad = 0;
double d_alt = alt;
double numDegrees = 0;
numDegrees = 360 / numPoints;
Angle curr = Angle.FromDegrees(0);
for (int i = 0; i < numPoints; i++)
{
curr.Degrees = (double)i * numDegrees;

lat_rad.Radians = Math.Asin(Math.Sin(lat.Radians) * Math.Cos(dist_rad) + Math.Cos(lat.Radians) * Math.Sin(dist_rad) * Math.Cos(curr.Radians));
dlon_rad = Math.Atan2(Math.Sin(curr.Radians) * Math.Sin(dist_rad) * Math.Cos(lat.Radians), Math.Cos(dist_rad) - Math.Sin(lat.Radians) * Math.Sin(lat_rad.Radians));
lon_rad.Radians = ((lon.Radians + dlon_rad + Math.PI) % (2 * Math.PI)) - Math.PI;

//This algorithm is limited to distances such that dlon <pi/2
points[i] = new Point3d(lon_rad.Degrees, lat_rad.Degrees, d_alt);
}

this is draw circle
how to draw Ellipse?