# bisecting an angle

Bisecting an angle is a splitting an angle exactly
in two using only a pair of compasses and a straightedge. This is easy and the ancient Greeks knew very well how to
do it. Put the point of the compass at a point *O* and draw a circle so that it cuts the two lines coming out from
the angle. Call these intersection points *A* and *B*. Now put the point of the compass at *A* and draw an arc that follows within the opening of the angle. Without changing
the radius at which the compass is set, move its point to *B* and
draw another arc. Join the point where the two arcs cross, *P*, to *O* using the straight edge: angle *POB* is half of angle *AOB*.