Page 86 - Start Up Mathematics_6

Segments of a circle
minor segment
The region in the interior of the circle enclosed by an arc and A B
the corresponding chord is known as a segment.
O
Chord AB of a circle divides it into two segments. The larger major segment
part is called the major segment and the smaller part is called
the minor segment of the circle. Also, the segment which
contains the centre of the circle is called the major segment and
the segment which does not contain the centre of the circle is
called the minor segment.
N
Circumference
The length of the boundary of the circle is its circumference.
In the adjacent figure, LMNL represents the circumference of Circumference O M
the circle.

Semicircle and semicircular region L
The diameter of a circle divides it into two equal parts, each X
part is known as a semicircle. Note that a semicircle is just
an arc with only the end points of the diameter lying on it. A Semicircular
semicircular region is a segment formed by the diameter of region
the circle. P O Q
Semicircular
In the adjoining figure, arcs PYQ and QXP represent semicircles region
and segments PYQ and QXP represent semicircular regions.
Y
Sector P
The region enclosed by an arc of a circle and two radii joining Minor
the extremities of the arc is called the sector of the circle. sector Q

The sector made by minor and major arcs of the circle are called O
minor and major sectors respectively. Major sector

Concentric circles
Two or more circles having the same centre are called concentric
circles.

O
Example 16: From the figure, identify:
(a) The centre of the circle (b) Three radii

(c) The diameter (d) Two chords X D
(e) Two points in the interior (f) A point in the exterior C
(g) Two sectors (h) A segment E
Solution: (a) O is the centre of the circle. O P Q
(b) Three radii are OE, OA and OC. R
(c) AC is the diameter.
A
B
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