oh, oh, oh
this is quite an interesting geometry puzzle i got once.
For equiangular quadrilateral ABCD, side CD is "x" units long. Connect these 4 points with the shortest amount of connecting as possible. For example, connecting point A, B, C, D with line AB, BC, CD, DA would have a distance of "4"
You could look on the internet, but that just spoils it
answer:
http://en.wikipedia.org/wiki/File:Steiner_4_points.svg