public Coordinate2D ControlPoint1 {get;}

{
  // retrieve the bezier curve's control points
  CubicBezierSegment cb = CubicBezierBuilderEx.CreateCubicBezierSegment(bezierSegment);
  MapPoint startPt = cb.StartPoint;
  Coordinate2D ctrlPt1 = cb.ControlPoint1;
  Coordinate2D ctrlPt2 = cb.ControlPoint2;
  MapPoint endPt = cb.EndPoint;

  bool isCurve = cb.IsCurve;
  double len = cb.Length;
}