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21 st
Activity Century #Experiential Learning
Skills

• Trace a circle using any circular object such as a big bottle cap or a bangle and
cut along the traced lines.
Cut a piece of string and wind it around the circle. Use a ruler to measure the
length of the string, which is equal to the length of the circle. The length of the
circle is called its circumference.

• Now, fold the circle in half and make a crease. Open it out.
The crease makes a line across the circle which is called the
diameter of the circle.

• Again, fold the half folded circle
in half as shown. We will get a
quadrant. Now open out the folds. Diameter
We will see four quarters meeting at
a common point. This point is called
the centre of the circle.
The line segment that joins a point
of the circle to the centre is called a
radius of the circle.
• A half circle is called a semicircle.

Centre Radius

parts of a Circle

Look at the circle and its parts given below:

Centre of the circle
O is the centre.The distance between point O
and any point on the boundary of the circle is equal.

Diameter
The diameter AB is the distance across a circle
O through its centre.
A B

Radius
The radius OR is the distance from the centre
to any point on the circle.

R Circumference
The circumference is the distance around the circle.

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Geometry