Circle:A circle is a simple closed shape. It is the set of all points in a plane that are at a given distance from a given point, the centre; equivalently it is the curve traced out by a point that moves so that its distance from a given point is constant. The distance between any of the points and the centre is called the radius.
1 Degree (of arc):1 degree of arc is define as 1/360 of a revolution. In SI units 1° is π/180 radians.