Как в WPF c# убрать линию между краями параболы?

        double b0 = -6.7;
        double b1 = 60.7;
        double b2 = -132.25;
        Polygon myPolygon1 = new Polygon
        {
            Stroke = System.Windows.Media.Brushes.Red,
            StrokeThickness = 2,
            HorizontalAlignment = HorizontalAlignment.Left,
            VerticalAlignment = VerticalAlignment.Center
        };

        double x1, y1;
        x1 = 50;
        while (x1 <= 550)
        {
            double t = ( 0.01 +(x1 - 50) / 500);                
            y1 = b2 * t  *t  + (b1 * t ) + b0;               
            Point p1 = new Point(x1,  380 - y1);
            pc1.Add(p1);
            x1 = x1 + 0.1;
        }
        myPolygon1.Points = pc1;
        canv.Children.Add(myPolygon1);