Using the protractor, draw a right angle. Bisect it to get an angle of measure 45°.

Steps of construction:

1. Draw an angle ABC of 90°.

2. With B as the centre and any radius draw an arc which intersects AB at P and BC at Q.

3. With P as center and radius more than half of PQ draw an arc.

4. With Q as center and same radius draw an arc which intersects the previous arc at R.

5. Join RB.

Therefore ∠RBC = 45°