Have you tried to convert the sides and points involved to mathematical variables? This is usually the first (and most important) step in solving these kinds of problems.
Can you help with the following problem?
Using a square sheet of paper:
- Choose a point, P on the top edge
- Join P to the bottom right-hand corner
- Create a 45 degree triangle in the top left hand corner, using P. What position, of the original point P, WILL MAKE THE AREA OF THE QUADRILATERAL a maximum?