@ Brian & Marco - it's not really necessary to do that type of arc construction, the circles that you create in MoI will already be made of 4 precise non-approximated arcs.

But when you turn on control points, it is assumed that you want to squish those points around and MoI will show you the points of a rebuilt circle that deforms smoothly rather than devolving into 4 arcs with sharp cusps between them.

The exact 4-arc circle will only be replaced by the deformable version if you actually edit any of the control points.

The same thing happens with surfaces of revolution as well.

- Michael