The Circle
By Ranjana
O A
CIRCLE
Eg. ball,bangle,lemon.coin
CENTRE
O
B A
RADIUS
CENTRE : O
RADIUS : OA
.
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
Radius
O A
The distance from centre to any point on the
circle is called radius of the circle.
RADIUS = OA
A
D
I
A
.
O M
E
T
E
R
B
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.
DIAMETER = AB
.
O
The length of the circle or the distance
around it is called circumference of the
circle.
A .
O
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
RADIUS = DIAMETER
2
A .
O
B
OB = AB
2
Eg. If diameter of the circle is 10 cm then find
its radius?
Sol. Radius =diameter / 2
radius=10 cm/ 2
radius =5 cm
A .
O
Diameter = 10cm B
Eg. If radius of the circle is 6 cm,then find the
diameter of the circle?
Sol. Diameter = 2 x Radius
Diameter = 2 x 6cm
Diameter = 12 cm
A
Radius = 6cm
.O
RELATION BETWEEN CIRCUMFERENCE AND
DIAMETER
CIRCUMFERENCE = 3 x DIAMETER(APPROX)
A .
O
DIAMETER
B
Eg. Find the circumference (approx) of the circle whose
diameter is 10cm.
Sol. Circumference = 3 x
diameter(approx)
Circumference = 3 x 10 cm
Circumference = 30 cm
A .
O B
DIAMETER=10 CM
EVALUATION
1. what is the relation between radius and diameter of the
circle?
Sol .Radius=diameter/2
2. What is the relation between circumference and diameter
of the circle?
Sol. Circumference=3Xdiameter(approx)
3. In this figure
radius
OA or OB is ______. A .
O
B
diameter
AB is ________.
centre
O 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.