
Solution:
b
Using a ruler and a compass, it is possible to
construct 75°. On constructing the angle bisector of
75°, we get the angle of 37.5°.
Using a ruler and a compass, it is possible to
construct
. On constructing the angle bisector of
45°, we get the angle of 22.5°.
Using a ruler and a compass, it is possible to
construct 90° and 45°. Thus, 135° can be constructed.