A piece of papers with dimensions 200*400 (pixels) as above is to be folded. We take the upper right corner and put it somewhere on the base line. Try this by clicking a little above the base line and the paper will fold.
Our aim is to achieve an area of 16000 for the folded triangular area. Explain how to do this. (Of course, the applet to the right is only for the fun, and for checking your result---in the paper you have to explain how to find the right dimensions using algebraic equations.)
Erich Prisner, September 2005