Circle

   A Circle is a simple closed figure all of whose points are at the same distance from a fixed point  O ( Centre of the circle) in the same plane.

• Radius is the line segment joining the centre of a circle to any point on the circle

• Chord is a line segment joining any two points on a circle.

• Diameter is a chord that passes through the centre of the circle. It is the longest chord in the circle. It is twice the radius.

• Circumference is the distance around a circle.

• Secant is a line which intersects or meets the circle at two distinct points.

• Arc is a part ( continuous) of a circle.

• A diameter divides a circle two equal parts which are called semicircles.

• A chord of a circle divides the area enclosed by it into two parts which are called Segments.

• Sector is the part of a circle enclosed by any two radii of the circle

• If the two radii are at right angles to each other the sector is called a quadrant.