CHAPTER 10 CIRCLES
The collection of all the points in a plane, which are at a fixed distance from a fixed point in the plane, is called a circle. The fixed point is called the centre of the circle.
The fixed distance is called the radius of the circle.
The chord that passes through the centre and joins two points on the circle is called the diameter.
Circumference: The length of the complete circle is called its circumference.
Segment: The region between a chord and either of its arcs is called a segment.
Sector: The region between an arc and the two radii joining the centre to the end points of the arc is called a sector.