How do I save a triangle object in lsit and draw again?

I am trying to save the triangle I drew and draw again while the previous triangle is still there. I did this in rectangle, square, circle and ellipse and it worked. I don't know why it won't in Triangle. IS there something wrong in the code?

What I have tried:

<pre>>This is how I draw and "save (not working)"

**Shape Class**    


        public void DrawTriangle(Color c, int stroke,PointF[] tpoints, float w, Graphics g)
        {
            this.width = w;
            this.strokeThickness = stroke;
            this.tPoints = tpoints;
            g.InterpolationMode = InterpolationMode.High;
            g.SmoothingMode = SmoothingMode.AntiAlias;
            g.DrawPolygon(new Pen(c, stroke), tpoints);
        }
**Form 1**  

        public void DrawTriangle()
        {
            tC = Color.Red;
            strokeTriangle = trackBar_Stroke.Value;
            tW = Convert.ToInt32((Convert.ToInt32(tbox_Width.Text) * 96) / 25.4);
            tH = (Convert.ToInt32((tW * (Math.Sqrt(3))) / 2));
            tX = (pictureBox_Canvass.Width - tW) / 2;
            tY = ((pictureBox_Canvass.Width - (tH)) / 2) + tH;

            float angle = 0;
            t_Points[0].X = tX;
            t_Points[0].Y = tY;
            t_Points[1].X = (float)(tX + tW * Math.Cos(angle));
            t_Points[1].Y = (float)(tY + tW * Math.Sin(angle));
            t_Points[2].X = (float)(tX + tW * Math.Cos(angle - Math.PI / 3));
            t_Points[2].Y = (float)(tY + tW * Math.Sin(angle - Math.PI / 3));
        }
        public void AcceptTriangle()
        {
            Shape shape = new Shape();
            tC = Color.Gray;
            shape.strokeThickness = strokeTriangle;
            shape.width = tW;
            shape.x = tX;
            shape.y = tY;
            shape.tPoints = t_Points;
            s._triangle.Add(shape);
        }

>This is how I iterate it.


    public List<Shape> _triangle = new List<Shape>();
    foreach(Shape shapes3 in s._triangle)
            {
                shapes3.DrawTriangle(shapes3.color, shapes3.strokeThickness, shapes3.tPoints, shapes3.width, e.Graphics);
            }