The bisector of an angle is a ray whose end point is the vertex of the angle and which divides the angle into two equal angles.
Steps of construction:
(a) Draw a ray OA.
(b) At O, with the help of a protractor, construct ∠AOB=153∘
(c) Draw ¯¯¯¯¯¯¯¯OC as the bisector of ∠AOB.
(d) Again, draw ¯¯¯¯¯¯¯¯¯OD as bisector of ∠AOC.
(e) Again, draw ¯¯¯¯¯¯¯¯OE as bisector of ∠BOC.
(f) Thus, ¯¯¯¯¯¯¯¯OC,¯¯¯¯¯¯¯¯¯OD and ¯¯¯¯¯¯¯¯OE divide ∠AOB in four equal arts.