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SAI International School

Class : VI

Mathematics

Chapter - 4 – Basic Geometrical Ideas

Lesson Note – 4.5

Subtopics:

 Circle
 Parts of circle

Definition Example

Circle and its  A circle is a simple closed
parts curve which is not a polygon.
 We can draw a circle using a
compass, bangles or using a
coin.
 The circle has a centre point.
 The perimeter of a circle is the
set of all points at a fixed
distance from the centre of the
circle called circumference.
 The distance from the centre of
the circle to the circumference
is called the radius of the
circle.
 A line segments joining any two
points on a circle is called a
chord.
 Chord passing through the
centre of the circle is called
diameter. Diameter is double
of the length of radius.
Diameter is the longest chord.
 A chord divides a circle into two
parts. Each part is called a
segment.
 A portion of the circumference
of a circle is called an arc.
 Portion of a circle enclosed by
two radii and an arc is called
sector, where the smaller area

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