- The set of all points in the plane that are a fixed distance (the radius, r) from a fixed point (the centre, O).
- The angle at the centre of a circle is 360°.
- A chord passing through the centre.
- D = 2r, twice the length of the radius.
Circumference of a Circle
- The circumference of a circle, AKA the perimeter, is given by:
c=2 \pi rRead More »2.1 Circles and Arcs