How to draw Triangle in ASP.NET Chart Control

Hi
I am looking for a control that can draw a very customized chart in ASP.NET.  The chart comprises:
1. A closed triangle, or polygon, shaded, drawn according to a fixed set of xy vertices.
2. A series of x,y points plotted on top of the triangle or polygon.
I thought the chart Control wasthe best, but I can't figure out how to draw the close triangle or polygon.
Is GDI+ the better way?
Thanks
 
Alan
...