Page 65 - Maths Class 06

Exterior and Interior of a Circle
In the circle with centre O (Fig 4.36), points P and Q are in the interior of the
circle, points M and N are on the circle, and points X and Y are in the ex te rior of M
the cir cle.
P O
The interior of the circle together with the circle is known as the circular region Q

The circular region is shown by the shaded portion in Fig. 4.36.
X
Y N
Fig. 4.36
Segment and Sector

Consider a circular disc and tear it off into
Minor Segment R
two pieces as shown in Fig 4.37 (b). Each
piece is called a segment of the circle. For
each circle, there are two segments,
O
namely a minor segment and a major
seg ment. Major Segment
A region enclosed by an arc and a pair of
P Q
radii of a circle is called the sector of the Y
A disc Two pieces of the disc
circle.
(a) (b) (c)
In the Fig 4.37 (c), the shaded portion Fig. 4.37
shows a minor sector corresponding to
the minor arc PYQ, whereas the unshaded portion is a major sector corresponding to the major arc QRP.

Let us summarize what we have just learnt (Table 4.1)

Part Description Example Properties

Centre A point in a plane from O is the centre A circle can have only one
which all points on the O centre.
circle are equidistant.

Radius A line segment with one OP is a radius P The radius is always half
endpoint at the centre the diameter. A circle can
O
and the other endpoint have an infinite number of
on the circle. radii.

Diameter A chord that passes AB is a diameter A diameter is twice the
through the centre of the A B length of the radius. It
circle. always passes through the
centre. It is the longest
chord of the circle.

Circumference The length of the Every point on the
boundary of a circle. O circumference is equi-
distant from the centre.

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