Steps of Construction-

1. Draw a line PQ and take a point O on it.

2. Taking O as centre and convenient radius, mark an arc, which intersects PQ at A and B.

3. Taking A and B as centers and radius more than half of AB, draw two arcs intersecting each other at R.

4. Join OR. Thus, ∠QOR = ∠POR = 90°

5. Draw OD the bisector of ∠POR. Thus, ∠QOD is required angle of 135°

6. Draw the bisector of ∠QOD. Hence,