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);