Hey guys, I have an idea on how to do this problem for certain cases - does anyone know how to show this for a general case (since thats what its asking for I think):

"If we have 4 points A,B,C, D which are given on a straight line (in that order), show how to construct a pair of paralllel lines through 'A' and 'B' and another pair of parallel lines through 'C' and 'D' so that the 4 lines intersect in a square"