Origami

Make a simple fold on an A4 paper.
How does the crease intersect with the sides of the square when B is folded onto a mid-segment?
How does the point E vary if the crease always passes through A?
How does the area of the (non)overlapping part vary?

Think of more questions about the fold.

Arthur Lee, 24/4/2006, Created with GeoGebra