The Circle

By Ranjana

O A

CIRCLEEg. ball,bangle,lemon.coin

OA

CENTRE : O

RADIUS : OA

BCENTRE

RADIUS

.O

In a plane,each point of the circle is at equal distance from a fixed point.The fixed point is called the centre of the circle.

CENTRE = O

O

The distance from centre to any point on the circle is called radius of the circle.

A

RADIUS = OA

Radius

.ODI AMETER

A Line segment passing through the centre of the circle and whose end points lie on the

circle is called the diameter of the circle.

A

B

DIAMETER = AB

.O

The length of the circle or the distance around it is called circumference of the circle.

.OA B

A Line segment whose both the ends touches the circumference and passes through the centre is called diameter.

DIAMETER : AB

Relation between radius and diameter

.OA B

RADIUS = DIAMETER

2

OB = AB

2

Eg. If diameter of the circle is 10 cm then find its radius?

.ODiameter = 10cm

Sol. Radius =diameter / 2 radius=10 cm/ 2 radius =5 cm

A B

.O

Eg. If radius of the circle is 6 cm,then find the diameter of the circle?

Radius = 6cmA

Sol. Diameter = 2 x Radius

Diameter = 2 x 6cm

Diameter = 12 cm

RELATION BETWEEN CIRCUMFERENCE AND DIAMETER

.ODIAMETER

CIRCUMFERENCE = 3 x DIAMETER(APPROX)

A B

Eg. Find the circumference (approx) of the circle whose diameter is 10cm.

.ODIAMETER=10 CM

Sol. Circumference = 3 x diameter(approx)

Circumference = 3 x 10 cm

Circumference = 30 cm

A B

EVALUATION1. what is the relation between radius and diameter of the circle?

.OA B

2. What is the relation between circumference and diameter of the circle?

3. In this figure

Sol .Radius=diameter/2

Sol. Circumference=3Xdiameter(approx)

radius

diametercentre

AB is ________.

O is _________.

OA or OB is ______.

This powerpoint was kindly donated to www.worldofteaching.com

http://www.worldofteaching.com is home to over a thousand powerpoints submitted by teachers. This is a completely free site and requires no registration. Please visit and I hope it will help in your teaching.