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\\November 23, 2023 10:09 AM Surender Prajapati Proof 5 Reader _________________________ Date: ___________________74

parts of a circle
Radius (OC)
There are different parts in a circle with special names. Circumference C

Š Centre: The fixed point inside the circle which Centre
(O )
is at equal distance from all points on the circle
is called the centre. Here, point O is the centre A B
Diameter O Q
of the given circle. (AB)
Š radius: The distance from the centre to any

point on the boundary of the circle is called its P Chord (PQ)
radius.

Here, OC, OA and OB are the radius of the given circle. Remember

Š diameter: The distance between two points of the A circle can have infinite
boundary of the circle that passes through the centre is radii of equal measure.
Radii is the plural of
called its diameter. Here, AB is a diameter of the given radius.
circle.

Š Circumference: The distance around a circle is called
its circumference. Knowledge Desk

Š Chord: A line segment whose end points lie on the The diameter AB is also
circumference of the circle is called a chord of the circle. a chord. Diameter is the
longest chord of the
Here, PQ is a chord. circle.

Š Semi-circle: The diameter divides a circle into two equal
halves. Each half is called a semi-circle.

Š relation between radius and diameter: The diameter of a circle is twice the radius
of the circle. The radius of a circle is half the diameter.

Diameter = 2 × Radius or Radius = Diameter
2

example 1: Find the diameter of a circle whose radius is 6 cm.
p u Z Z L E
Solution: We have, Diameter = 2 × Radius
Connect all the given
Therefore, Diameter = 2 × 6 cm = 12 cm dots without lifting

example 2: Find the radius of a circle whose diameter is 8 cm. your pencil using
exactly four line

Solution: We have, Radius = Diameter segments.
2
8
Therefore, Radius = = 4 cm.
2

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