#Polygon

Key G. A regular polygon; the number of sides and the way it is fitted are set in the top bar.

The first click places the centre, the second a vertex or the middle of a side, depending on what is chosen above.

#What you get

The sides are tied by equal length and by angles, so the polygon is defined by a centre and one dimension — the radius of the circumscribed or of the inscribed circle.

#A hint

A hex for a spanner is easier to set by the inscribed circle: the across-flats size is exactly the distance between opposite faces, that is twice the inscribed radius.