Page 98 - Revised Maths Wisdom Class - 6

96 MATHS

So, ∠LOR > ∠PAQ
R
Q

O(A) L(P)

Measurement of Angles
We measure angles in degrees. The symbol for degree is ‘°’. A
complete turn around a point is divided into 360 equal parts. Each of
these parts is called a degree and is denoted by 1°. We use a special
geometrical tool to measure angles called protractor. It looks like
as shown.
The protractor is in the shape of a semi-circle and the midpoint of its
horizontal edge or base line is called its centre. A protractor has two
scales—inner and outer. One scale begins with 0° on the right and Centre base line
moves to 180° on the left. The other scale starts with 0° on the left
and moves to 180° on the right. The smallest division on a protractor is equal to 1°. To measure an angle ∠ABC
using protractor, we follow these steps:
Step 1: To measure ∠ABC, place the protractor in such a way that its centre lies C
on B and the arm BA coincides with the horizontal edge or base line of the
protractor.

Step 2: Starting from 0° of the inner scale, move towards point C and note the mark
on the rim of the protractor where ray BC passes. B A

Step 3: Read the mark carefully taking care of smaller divisions also.
C

Thus, ∠ABC = 65°
B A

Exercise 6B
Exercise 6B
1. Measure the angles given below using the Protractor and write down the measure.
(a) (b) (c) (d)