First, draw an angle of `80^(@)say angleQOA = 180^(@)` with the help of protractor. Now, use the the following steps to construct angles of
f `(i) 40^(@) (ii) 160^(@) and (iii) 120^(@)` .
(i) Taking O as centre and any radius an which intersect OA at E and OQ at F .
(ii) Taking E and F as centres and radius more than `(1)/(2)EF` draw arcs which intersect each other at P.
(iii) Join OP. Thus, `anglePOA = 40^(@) [because40^(@)=(1)/(2)xx80^(@)]`
(iv) Now, taking F as centre and radius equal to EF draw an arc which intersect previous arc obtained in step ii at S .
(v) Join OS. Thus, `angleSOA = 160^(@) [because160^(@)=2xx80^(@)]`
(vi) Taking S and F as centre and radius more than `(1)/(2)SF` draw arcs which intersect each other at R. ,
(vii) Join OR. Thus , `angleROA = angleROQ = 40^(@) + 80^(@) = 120^(@)`
