Constructs an ellipse with the specified center, major and minor axes, major and minor radii, and start and end angles. 

The angle of a point on the ellipse is measured by drawing a full circle with the same center as the ellipse, with a radius equal to the ellipse major radius, and projecting the point onto the circle along a vector perpendicular to the major axis. If a vector is then drawn from the ellipse center to this projected point, the angle between the major axis and this vector (measured counterclockwise about the cross product of the major and minor axes) is the angle of the point on the ellipse. 

endAngle must be greater than startAngle. To construct a full ellipse, the difference between endAngle and startAngle should be 2 x Pi. 

Public Sub New(
    center As Point3d, 
    majorAxis As Vector3d, 
    minorAxis As Vector3d, 
    majorRadius As double, 
    minorRadius As double, 
    startAngle As double, 
    endAngle As double
)

public EllipticalArc3d(
    Point3d center, 
    Vector3d majorAxis, 
    Vector3d minorAxis, 
    double majorRadius, 
    double minorRadius, 
    double startAngle, 
    double endAngle
);