> I would love to have this information. At one timeI knew > how to do this, but I have forgotten.
Here's what I call the "BISECT-BISECT" construction, which is one of the simplest. I suppose that you want to draw your pentagon ABCDE in the circle with center O whose Northernmost, Southernmost, Easternmost and Westernmost points are NSEW, with one vertex being at E:
N | A B | | | Y | | | \ | | | \| W--Z--------O---X--------E | | | | | | | | | C | | | D S
What you do is BISECT the segment NO at Y, and then BISECT the angle OYE; letting the internal bisector YX cut OE in X and the external one YZ cout OW in Z. Then the perpendiculars to WE through these points hit the circle in the four other vertices A,B,C,D as shown.