Hi 3d2cnc, is it possible for you to post the .3dm model file so I could take a look?

How are you creating the polygon to begin with? There is a polygon drawing tool under Draw Curve > Polygon > Star which is an easier way to make an exact star shape like that rather than moving individual points around.

If you did want to do it with manual placement of points, I'd probably try drawing a circle and some lines to set up some intersection snap points.

- Michael