Page 60 - Mathematics Class - IX

ACTIVITY 4.6

OBJECTIVE

To verify that “The angle subtended by the arc at the centre of the circle is double the angle subtended by it at
any other point on the circumference of the circle”.

MATERIALS REQUIRED

Tracing paper
Coloured paper

A ruler
A pencil

A pair of scissors

PRE-REQUISITE KNOWLEDGE
Angle made by an arc at the centre and at circumference.

THEORY

1. Circle: The collection of all the points in a plane, which are at a fixed distance from a fixed point in the
plane is called a circle.

2. Diameter: The chord, which passes through the centre of the circle, is called a diameter of the circle.
or

A diameter is the longest chord and all diameters have the same length, which is equal to two times the
radius.
3. Circumference: The length of the complete circle is called its circumference.

4. Arc: A piece of a circle between two points is called an arc.
The longer one is called the major arc and the shorter one is called the minor arc.

5. Segment: The region between a chord and either of its arcs is called a segment of the circular region or
simply a segment of the circle.
There are two types of segments, which are the major segment and the minor segment.

R

Major arc PQ
Major segment

P Q

P Minor arc PQ Q P Minor segment Q

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