There is a subtle flaw with the given construction of a trisection. The points W,X,Y,Z have to be chosen more carefully than the problem specifies; the danger is that there might not be a point D satisfying the desired conditions (AE=AD and lines AW, DZ are parallel). You can test this by dragging E around and observing that the points B,C,D sometimes disappear. The fix (which will go in the next edition of the problem list!) is to put an additional condition on the points W,X,Y,Z that depends on A and E. What this condition is, I will leave this as part of the problem, but it's nothing too complicated. Another note: The quintasection you construct should work for any arbitrary line segment. That is, start by drawing two points A,F at random and connecting them with a segment. This is the segment that you want to quintasect - everything else should ultimately be defined in terms of these two points.