Page 155 - Maths Class 04

Terms for a Circle

Centre : In the circle, there is a point from which the distance of every point
on the boundary of the circle is equal. This point is represented by a capital

alphabet ‘O’ and it is called the centre of the given circle.

O

Radius : The distance of the centre from a point on the boundary of the

circle is called the radius of the circle.

B

D A
O

C

The distance OA, OB, OC, OD represent the radii of the given circle. Radius is
denoted by r or R.

Diameter : The diameter of a circle is double of its radius. It is denoted by d

or D. Indefinite numbers of radius and diameters can be drawn from the
centre of a circle.

Diameter = 2 × Radius

A B
O Diameter
Radius =
2

AB is called the diameter of the given circle.

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