In the picture all of the red segments are of equal length and all of their endpoints lie on one of the two blue lines. Determine all possible values for the smaller angle between the blue lines.

(This problem is a special case of a problem discovered by Daniel Shapiro, professor of mathematics at Ohio State University. His problem generalizes a problem he saw years ago.)

(In reply to re(2): Label the figure (Solution) by Eric)

You seem to assume that the figure is symmetrical about a vertical line through O (angle CAB=angle FDE) but you don't say why.

Posted by McWorter on 2005-06-09 16:41:00