1. The Circle
By Ranjana

2. O A
CIRCLE
Eg. ball,bangle,lemon.coin

3. O
A
CENTRE : O
RADIUS : OA
B
CENTRE
RADIUS

4. .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

5. O
The distance from centre to any point on the
circle is called radius of the circle.
A
RADIUS = OA
Radius

6. .O
DI
A
M
E
T
E
R
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

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

8. .O
A B
A Line segment whose both the ends touches
the circumference and passes through the
centre is called diameter.
DIAMETER : AB

9. Relation between radius and
diameter
.O
A B
RADIUS = DIAMETER
2
OB = AB
2

10. Eg. If diameter of the circle is 10 cm then find
its radius?
.O
Diameter = 10cm
Sol. Radius =diameter / 2
radius=10 cm/ 2
radius =5 cm
A B

11. .O
Eg. If radius of the circle is 6 cm,then find the
diameter of the circle?
Radius = 6cm
A
Sol. Diameter = 2 x Radius
Diameter = 2 x 6cm
Diameter = 12 cm

12. RELATION BETWEEN CIRCUMFERENCE AND
DIAMETER
.O
DIAMETER
CIRCUMFERENCE = 3 x DIAMETER(APPROX)
A B

13. Eg. Find the circumference (approx) of the circle whose
diameter is 10cm.
.O
DIAMETER=10 CM
Sol. Circumference = 3 x
diameter(approx)
Circumference = 3 x 10 cm
Circumference = 30 cm
A
B

14. EVALUATION
1. what is the relation between radius and diameter of the
circle?
.O
A 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
diameter
centre
AB is ________.
O is _________.
OA or OB is ______.

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