This subpanel creates a nodes at the center of the arc that best approximates the input set of nodes, points or lines.

For nodes and points input, a minimum of three must be selected.

For lines input, the selection must not result in a straight line.

An existing arc is an ideal input.

However, almost any set of lines will also work, even if they are not connected, as long as they do not form a straight line.

An optional tolerance is available to verify whether the calculated best-fit circle is sufficient.  If ignored, the best-fit circle is always calculated; otherwise, an error is returned if the input entities are not all on the circle within the specified tolerance.