Which of the following angles can be constructed without using a protractor?
30∘
Angles 60o and 30o can be constructed using a scale and compass.
1. Draw a line l.
2. With O as centre and with any convenient radius, draw an arc to cut line l at A.
3. With A as centre and with the same radius, draw an arc to cut the previous arc at B.
4. Join OB and extend. ∠AOB= 60o
5. To construct 30o we bisect 60o.
The remaining two angles cannot be constructed without using a protractor.