Page 64 - Maths Class 06

Segment : When a chord divides a circle into two parts, each part is called a segment
A
of the circle. segment
Major
In Fig. 4.30, the chord AB divides the circle into two parts, each of these parts is
called a segment of the circle. The smaller, i e. . the shaded part of the circle is called Major
O
the minor segment and the larger, i e. . the unshaded part of the circle is called major segment B
segment.
Fig. 4.30
NOTE

The major segment contains the centre of the circle whereas the minor segment does not
contain the centre of the circle.

Arc : An arc is a part of the circumference of the circle. It is denoted by the symbol ‘ ’
A
Let Aand B be two points on the circumference of the circle as shown in Fig. 4.31. On C
joining AB with a straight line, the circumference of the circle is divided into two Minor arc
parts, namely ACB and ADB. These two parts are known as arcs of the circle and B
O
denoted by ACB and ADB. Major arc
An arc is a part of a circle and is usually denoted by three points. D

From the figure, we observe that the length of arc ACB is smaller than the length of Fig. 4.31
arc ADB. Therefore, arc ACB is called the minor arc and arc ADB is called the major
arc.

Concentric Circle O

Two or more circles with same centre are called concentric circles.

Fig. 4.32
Sector : The part of a circle enclosed by any two radii of the circle is called a sector. Y
In Fig. 4.33, is shown a circle with centre O. A and B are two points on the circle. OA Major
and OB are two radii. These radii divide the circle into two parts each being a sector of sector
O
the circle. The sector formed by the major arc AYB is called the major sector and the
sector formed by the minor arc AXB is called the minor sector.
A B
X
Semicircle : The endpoints of a diameter of a circle divide Semicircle Minor sector
the circle into two parts, each part is called a semicircle. Fig. 4.33
A B
In Fig. 4.34, the chord AB is the diameter of the circle. The

points A and B divide the circle into two equal parts. Each Semicircle
part is called a semicircle.
Fig. 4.34
A B
O
The part of the plane consisting of the diameter AB, the semicircle AXB and the
interior of the circle enclosed by the diameter B is called the semicircular region.
X
Fig. 4.35
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