I have a strip of paper with parallel sides, a pencil and a straight edge.
How can I construct a regular pentagram (star) with these? And for that matter, a pentagon? Well ... the pentagon is the proper way to go.
(In reply to A trick
by Brian Smith)
Is this the solution intended? If not, please advise that you are interested in a solution that does not require folding (or some other useful constraint).
P.S. Brian Smith, where'd you first observe this "trick", and in what context?
P.P.S. And all, who wishes to 'prove' that the method works, and that the only requirement is that a particular ratio (the one found by fwaff, here, is met?