The correct answer is:
We will use an edge of the given angle to construct another angle, with the same vertex; we will call that vertex O.
Mark an arc through the sides of the angle. Name the points where the arc intercepts the angle A and B; extend the arc past B.
Set the compass at point B. Open it to the width of AB.
With the compass still set on point B, mark an arc to intersect the first arc at a point C.
Now you have two congruent segments, AB = BC.
Since the distance OA=OB=OC, ∠AOB and ∠BOC are congruent.