The answer really depends on the tools you have available for use and the accuracy you want.
Personally, I would use CAD. I have a bunch of macro routines in my FastCAD program that allow me to quickly draw a regular polygon with any number of sides, at any angle, either inscribed or circumscribed on a given diameter circle. I just enter the various numbers (inscribed or circumscribed, diameter, number of sides, angle to one corner) and then click on a location. Done.
If you are drawing by hand and have a drawing board, compass, T-square, and 30/60/90 triangle, you can first draw a 3" diameter circle. Then draw three lines through the center of that circle, one horizontal with the T-square and two at 60 degree angles to that one using the triangle resting on the T-square. Finally, draw perpendiculars to those lines at the points they intersect the circle: again, the triangle will help with this by using the opposite angle resting on the T-square for four of them and the 90 degree angle for the other two (verticals). Be sure to extend these lines to meet at the six corners of the hexagon.
If you only have a compass and a right angle, first draw the 3" circle. Then, with the same setting of the compass, step off six equally spaced points arount the circle. Connect opposite pairs of these points with lines passing through the center. Finally use the right angle to draw perpendicular lines to these three lines at the points they intersect the circle. Be sure to extend these lines to meet at the six corners of the hexagon.
Many other ways, depending on what you have.
Paul A.
Make it fit.
You can't win and there is a penalty for trying!