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E:\Working\Focus_Learning\Math_Genius_5_(05-10-2023)\Open_Files\CHAP_06
\\November 23, 2023 10:09 AM Surender Prajapati Proof 5 Reader _________________________ Date: ___________________74

Remember
Clockwise means moving in the direction of the hands of a clock.
Anticlockwise is a direction opposite to that of the normal
rotation of the hands of a clock.
Clockwise Anti-clockwise

measuring an angle using protractor
B
Let us measure given angle ∠AOB using a protractor. To measure an angle
using protractor, follow the steps given below.
Step 1: Place the centre point of the protractor on the vertex O of the angle. O A

Step 2: Adjust the protractor in such a way that the
80
base line coincides with the arm OA of the 60 120 110 100 90 100 70 120 B
70
110
90
80
angle. 40 140 50 130 60 50 130 40 140
Step 3: Check the scale where the baseline arm points 20 30 150 30 150 160
to 0°. 10 170 160 20 10 170
Step 4: Read the measure of the angle where the 0 180 O 0 180 A
other arm crosses the scale.
Note
Here, arm OB passes through the mark between When we measure an angle
40° and 50°, i.e., 45°. clockwise, we use upper mark

Thus, the measure of given ∠AOB = 45°, i.e., ∠AOB scale and when we measure
= 45°. the angle anticlockwise, we
use lower mark scale.
drawinG an anGle with 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 Step 3: Mark a point Q on the paper
its centre point is at O and adjust against 60° of the scale. This
the protractor so that the baseline locates the position of point Q.
is along OP.

Q
70 80 90 100 110 70 80 90 100 110
90
60 120 110 100 80 70 120 60 120 110 100 90 80 70 120
50 130 60 50 130 50 60 130
40 140 40 140 40 140 130 50 140
30 150 40
150 30 30 150 30 150
20 160 20 160 20 160 20 160
10 170 10 170 10 170 10 170
0 180 O 0 180 P 0 180 O 0 180 P

Step 4: Now, remove the protractor and join Q
O and Q with the help of a ruler.

Thus, we have ∠POQ = 60° as the
required angle. 60°
O P

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