Using a wide pen, how do I draw a series of line segments with rounded corners

The LineJoin property of the Pen class allows you to specify how two lines should be joined. The following code segment produces the picture below.

  private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
  {
    Pen redPen = new Pen(Color.Red, 20);
      
    int startX = 20;
    int startY = 60;
    int width = this.ClientSize.Width / 17;
    int height = this.ClientSize.Height / 2;

    foreach(LineJoin LJ in new LineJoin[] { LineJoin.Bevel,
                         LineJoin.Miter,
                         LineJoin.Round})
    {
      redPen.LineJoin = LJ;

      Point[] points = {new Point(startX, startY),
                  new Point(startX + width, startY + height),
                  new Point(startX + 2 * width, startY),
                  new Point(startX + 3 * width, startY + height),
                  new Point(startX + 4 * width, startY)};

      e.Graphics.DrawLines(redPen, points);
      e.Graphics.DrawString( LJ.ToString(), new Font('Arial Black', 13), 
        new SolidBrush(Color.Blue), startX - 5, startY - 50);
      startX += 4 * width + 40;
    }
  }