In previous posts we talked about circumscribable segments. Now, we talk about properties of circular arcs. An arc of a circle is a portion of a circle bounded by two points. The circumference, in turn, is the set of all points equidistant from a central point in a plane. One of the properties is the congruence of arcs. Two arcs are congruent (that is, they have the same measure) if they subtend congruent central angles. This is useful, for example, in constructing regular polygons inscribed in a circle, where all sides and angles are equal.