1) A circle is a closed curve in a plane consisting of all points equidistant from a fixed point called the centre. 2) Key elements of a circle include the radius, diameter, circumference, chord, arc, and sector. The radius is the distance from the centre to the edge, and the diameter is twice the radius. 3) A circle can be divided into arcs, chords, sectors, and segments by drawing lines within the circle. An arc is a portion of the circumference, a chord connects two points on the edge, and a sector is the region between an arc and its radii.

1. SMP 1 KUDUS
Circle
MATHEMATICS
GRADE : 8

2. S
Circle in daily life Q
Circle in music Q
Ch ord P
Circle in sports
P
Circle
Centre Diameter DE
D E
Circumference M O
Circular region O Centre
u s
di
Radius Ra
Diameter F
M
Chord
RE
Arc G A rc
Sector
Semicircle
Segments of a circle
Crossword

3. A circle
BACK

4. Many musical instruments have a circular surface.
For example:
Bingo Drum Tabla
BACK Snare Drum Bass Drum

5. A circle
BACK Five rings in the logo of Olympic games

6. A circle is a closed curve in a plane.
A circle can be drawn with the help of a circular object.
For example: A circle drawn with the help of a coin.
BACK

7. A circle is a closed curve
consisting of all points
A circle
in a plane which are at the
same distance (equidistant)
from a fixed point inside it.
Centre O
This fixed point (equidistant)
inside a circle is called centre.
A circle has one and only one
centre.
BACK

8. A
Centre
A circle
O
The distance around a circle is called its circumference.
Formula of circumference: C = π d C = 2 π r BACK

9. A circle divides a plane into three parts.
3. Exterior of a circle
Centre
O
2. Interior of a circle
1. The circle
A plane
The interior of a circle together with its circumference
is called the circular region. BACK

10. O Centre
i us
R ad
M
A point on the circle
A line segment that joins any point on the circle to its centre is
called a radius.
(Contd…)

11. (Contd…)
N
Centre O
u s
di M
Ra
K
L
 Radii ( plural of radius) of a circle are equal in length.
 Infinite number of radius can be drawn in a circle.
BACK

12. A
O Centre
A circle
Diameter AB
B
A line segment that joins any two points on the circle and passes
through its centre is called a diameter.
(Contd…)

13. (Contd…)
M
A
A circle
P
O
Centre
Q
B
N
 Infinite number of diameters can be drawn in a circle.
 As the radii of a circle are equal in length, its diameters too
are equal in length.

14. (Contd…)
Diameter MN
M N
Radius OM O Radius ON
Centre
Radius OM = Radius ON
Diameter MN = Radius OM + Radius ON
The length of the diameter of a circle is twice the length of its
radius.
BACK

15. A is a point on the B is another point
circle on the circle
A
A line seCment th
g hord at joins B
point A and B
O
A line segment that joins any two points on the circle is called a
chord.

16. M
Cho
rd M
N N
O
C D
Chord CD
Diameter CD
K
L
Chord K
L
Diameter is also a chord of the circle.
(Contd…)

17. M N
Chord MN
O
C D
Diameter CD
K L
Chord KL
C D
M N
The diameter is the longest chord.
(Contd…)

18. M N
Chord MN
G
Ch O Centre
or
d
GH
K
L
Chord KL
H
Infinite number of chords can be drawn in a circle.
BACK

19. K L
O
Centre
An arc is the distance between any two points on the
circumference of a circle.
(Contd…)

20. Naming an arc
X
Arc KXL
K L
O
Centre
An arc is named by three points, of which two are the end points
of the arc and the third one lies in between them.
Formula of Arc length: θ/360 * πd
(Contd…)

21. X
Minor Arc KXL
K L
O
Centre
Major Arc KYL
Y
An arc divides the circle into two parts: the smaller arc is called
the minor arc, the larger one is called the major arc.
(Contd…)

22. An arc
An arc
BACK

23. X
K L
O
Centre
Formula of Area sector: θ/360 * πr2
BACK

24. S Semicircle DSE
Arc DSE
Diameter
D E
O
Centre
R Semicircle DRE
Arc DRE
 Half of a circle is called a semicircle.
 A semicircle is also an arc of the circle. (Contd…)

25. Semicircle DSE
Semicircular region
O Diameter E
D
Centre
Semicircular region
Semicircle DRE
The diameter of a circle divides it into
2 semicircular regions.
BACK

26. S
Minor segment of a circle
D E
Chord DE
Centre
O
Major segment of a circle
R
A chord divides the circular region into 2 parts, each of which is
called a segment of the circle. (Contd…)

27. P Minor arc DPE
D E Minor segment of
Chord DE the circle
Centre
O
Major segment of the
circle
Major arc DQE
Q
 The part of the circular region enclosed by a minor arc and
major
the chord is called a minor segment.
major
 Minor segment does not the centre of the circle. circle.
Major contains contain the centre of the
BACK

28. O
Centre
Semi
Radius Diameter Chord Arc Circle

29. O Centre
s OM
u
di
Ra
M
Semi
Radius Diameter Chord Arc Circle

30. Diameter DE
D E
O
Centre
Semi
Radius Diameter Chord Arc Circle

31. Q
Q
Ch o rd P
P
O
Centre
Semi
Radius Diameter Chord Arc Circle

32. E
O
Centre
R
PQ
Arc F
G
Semi
Radius Diameter Chord Arc Circle

33. S
Semicircle DSE
Semicircle
Diameter
D E
O
Centre
Semicircle
Semi
Radius Diameter Chord Arc circle

34. 2C
1A Across:
4D I A M E T E 3R 4. The line segment that joins any
R A two points on the circle and
R
passes through its centre.
5C I R C L E D 5. A closed curve in a plane.
6. All points on the circle are
U I equidistant from this point.
M 7. A line segment that joins any
U
two points on a circle.
F S
E
Down
6C E N T R E 1. The distance between any two
points on the circumference of the
E circle.
N 2. The distance around the circle.
7C H O R D 3. The distance from the centre of the
circle to a point on the circle.
E