Question:
Draw an angle of 80° with the help of a protractor and bisect it. Measure each part of the bisected angle.
Solution:
Steps of construction
1. Draw $\angle \mathrm{AOB}=80^{\circ}$ using protractor.
2. With O as centre and a convenient radius, draw an arc cutting AO at N and OB at M.
3. With N as centre and a convenient radius, draw an arc.
4. Similarly, with M as centre and same radius, cut the previous drawn arc and name it as point C.
5. Join OC.
OC is the required angle bisector.
On measuring we get
$\angle \mathrm{AOC}=\angle \mathrm{BOC}=40^{\circ}$