Page 123 - Math Genius C5

E:\Working\Orange_Education\Math_Genius_5\Open_Files\CHAP_06
\ 08-Oct-2025 Bharat Arora Proof-9 Reader’s Sign _______________________ Date __________

Here, arm OB passes through the mark Be Aware
between 40° and 50°, i.e., 45°. When we measure an angle clockwise,
Thus, the measure of given ∠AOB = 45°, we use the outer scale and when we
i.e., ∠AOB = 45°. measure the angle anticlockwise, we
use the inner scale.
drawinG an anGle with a protractor

Let us draw an angle of 60°. We follow the steps given below.
Step 1: Draw a line segment OP with the help of a ruler. O P

Step 2: Place the protractor on OP so that its centre point is at O and adjust the protractor
so that the baseline is along OP.

70 80 90 100 110
90
60 120 110 100 80 70 120
50 60 130
40 140 130 50 40 140
30 150 30 150
20 160 20 160
10 170 10 170
0 180 O 0 180 P
Step 3: Mark a point Q on the paper against the 60° mark of the scale. This locates the
position of point Q.

Q
80 90 100 110
70
60 120 110 100 90 80 70 120
50 60 130
40 140 130 50 40 140
30 150 30 150
20 160 20 160
10 170 10 170
180 0 180
0 O P
Step 4: Now, remove the protractor and join O and Q with the help of a ruler.
Thus, we have ∠POQ = 60° as the required angle.

Q

60°
O P

Be Aware
The measure of an angle is not affected by the length of the arms of the angle.

C
C
C

60° 60° 60°
O B O B O B

Mathematics-5
Mathematics-5 121121