Draw an angle of 140∘ with the help of a protractor and bisect it using ruler and compass.
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:
Step I: Draw an angle ∠B=140∘
Step II: With B as a centre and using a compass, draw an arc which cuts both rays of ∠B at A and C.
Step III: With A as centre, draw (in the interior of ∠B an arc whose radius is more than half the length of AC
Step IV: With C as centre and with the same radius and draw another arc, in the interior of ∠B let the two arcs intersect at D. Then ¯¯¯¯¯¯¯¯¯BD is the required bisector of ∠B.