Ex 14.6, 9 Draw an angle of 40 °. Copy its supplementary angle.
Let’s first draw a rough figure
So, lets first draw 40°
We follow these steps
Draw a line with point O & A on it
2. Place center of protractor on point O,
and coincide line OA and Protractor line
Mark point B on 40°
Join OB
∴ ∠ AOB = 40°
Now, we need to make a copy of its supplement.
Let’s follow these steps
Draw a ray OP
2. In our ∠ AOB,
From point O, draw an arc of any radius
on the supplement of 40°,
intersecting the sides at D & E
3. Using compass opened the same length,
draw an arc with point O as the center,
cutting OP at Q
4. Now, back to our angle ∠ BOA.
Open compass to length DE
5. Keeping the same radius,
Put pointed end of compass on point Q, and draw an arc.
The point where it cuts previous arc is point R.
6. Join OR
Thus, ∠ ROQ is the copy of ∠ BOA = 70°
6. Join OR
Thus, ∠ ROQ is the copy of ∠ BOA = 70°

Made by

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths and Science at Teachoo.