Definition of a Circle

The Circle is a collection of all the points in a plane, which are at a fixed distance from a fixed point in the same plane.

Euclid’s Definition of Circle

A circle is a plane figure bounded by one curved line, and such that all straight lines drawn from a certain point within it to the bounding line are equal. The bounding line is called circumference and the point is called the centre.

The figure indicates the depiction of a circle. In the circle as shown in the figure, the fixed point O is called the centre of the circle.

Radius of a Circle

The distance from any point on a circle to the centre is called radius of the circle. The radius of a circle is represented by the letter r.


In the figure, the radius of the given circle is denoted by the line OP, drawn from the point P on circle to the centre O. There are infinite number of points present in a circle. Therefore, for a given circle, an infinite number of radii can be drawn and all the radii are of equal length.

Chord of a Circle

The chord of a circle can be defined as the straight line that connects any two points in the circle. For a given circle, there is an infinite number of Chords. In the figure, the straight line RS drawn from the point R to S is a chord of the circle.

Rate this Article post
Love this Post? Share with Friends

Leave a Comment