A circle is defined as a set of points in a plane that are all the same distance (the radius) from a central point (the center). Common examples of circles include the rims of buckets, drums, and clocks. Key terms related to circles include: - Chord: A line segment connecting two points on the circle. - Diameter: The longest chord that passes through the center. - Circumference: The distance around the outside of the circle. - Arc: Any part of the circle. A minor arc is smaller than a major arc. - Segment: The parts that a chord divides the circle into. A minor segment is smaller than a major segment. - Central angle

1. Basic terms… Circles
By Rashmi Kathuria

2. Basic terms related to circle

3. What is a circle?
A circle is a locus of a
point in a plane which
moves such
that its distance from
a fixed point in the
same plane remains
constant.
The fixed point is
called the centre of
the circle and the
fixed distance is
called the radius.
O
P
Here O is the centre and OP
is the radius.

4. The bottom and top of a
bucket is usually a circle.
A playing drum is circular.
A clock is usually circular.
The top of the table
shown below is a circle.
Look around you! There are circles everywhere!

5. Centre & radius
Chord
Minor arc & major
arc
Diameter
Minor segment &
major segment
Central angle
Circumference
Circular region
Sector

6. A line segment joining
any two points
on the circle is called a
chord of a circle.
O
Here AB is a chord .
A B
Chord

7. A chord passing through
the centre of the circle is
called the diameter . It is
the longest chord.
A B
C
D
Here AB is diameter.
Diameter

8. The circumference of a
circle is the distance
around the outside of it.
Here light blue portion is circular
region.
Circumference

9. A circle along with its
interior is called the
circular region.
Circular region
Circular region

10. Any two points of the circle divide the
circle into two parts called the arcs .
The smaller part is called the minor arc
and the larger part is called the major
arc. In case the two parts are equal each
one of them is called a semicircle. .
Horizontal lines region
is the minor segment and
the remaining circular region
is the major segment
Minor arc ,
Major arc

11. A chord divides a circular region into
two parts called the segments of the
circular region. The smaller segment is
called as minor segment and the larger
segment is called as the major segment.
Horizontal lines region
is the minor segment and
the remaining circular region
is the major segment
Minor Segment,
Major Segment

12. The angle subtended
by an arc at the centre
of the circle is called
the central angle.
A
B
Central angle

13. A
B
Corresponding to a given arc, the
region bounded by the
two radii and the arc itself.Sector