public Coordinate2D ControlPoint1 {get; set;}

{
  // retrieve the bezier curve's control points

  CubicBezierBuilderEx cbbEx = new CubicBezierBuilderEx(bezierSegment);
  MapPoint startPtEx = cbbEx.StartPoint;
  Coordinate2D ctrlPt1Ex = cbbEx.ControlPoint1;
  Coordinate2D ctrlPt2Ex = cbbEx.ControlPoint2;
  MapPoint endPtEx = cbbEx.EndPoint;

  // or use the QueryCoords method
  cbbEx.QueryCoords(out startPtEx, out ctrlPt1Ex, out ctrlPt2Ex, out endPtEx);
}