Page 158 - Start Up Mathematics_5

P
(d) Two adjoining right angles form a straight angle.
∠SQR is a straight angle.

1 Identify the following as ray, line or line segment. S Q R

(a) (b) (c)
P Q R S C D

(d) (e) (f)
L M P N X Y

2 Draw the following lines.

(a) Slanting line (b) Vertical line (c) Horizontal line (d) Curved line

3 Classify the following as acute, obtuse, right or straight angle.

O P C
(a) (b) (c) D

A B Q
R O

L M
(d) (e) T (f) K
O
N S
I J

Measuring Angles Using a Protractor

We have learnt about different types of angles. Angles are measured in degrees. The symbol
used for degrees is ‘ ° ’. Now let’s learn how to measure them using a protractor.

inner scale

outer scale Know More

A protractor is also called
Dee as it resembles the
shape of the letter D.
O
base line centre point

A protractor has two scales of measurement—an inner scale and an outer scale. Both have
markings for angles from 0° to 180° in different directions.

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