Circle

A **circle** is a plane figure, bounded by a single curve line called its **circumference**, every part of which is equally distant from a point within it, called the **center**.

A **circle sector** is any piece of the circle between two radial lines (shaded in both dark and clear grey).

A **segment of a circle** is the region between a chord of a circle and its associated arc (shaded in dark grey).

An **annulus** is the region lying between two concentric circles

**Areas**