Rotating 22.5 degrees?

Does anybody know of a way to rotate a polygon (or any shape) by a specific number of degrees?

I’m designing a shape for a gothic cinquefoil arch (I’m actually going to be turning this into a tutorial) - I’ve completed the steps but I need to fit an octagan into a circle, pointing upwards. When you master a polygon in LB it points left or right and the only way to correct it is to rotate it 22.5 degrees.

My workaround is to draw a polygon with the line tool as below which is fine but it takes a bit longer as you have to snap each point of the line to vertical and horizontal reference points. Anybody got any ideas on how to improve this?