Folded square

This square piece of paper has been folded and creased. Where does the crease meet the side AD?

Problem



This 8 cm by 8 cm square of paper has been folded so that the corner at B lies exactly on top of E, the midpoint of CD. The dotted line shows the crease left by this fold.

 

Image
Folded Square



How far from A does the dotted line reach the side AB?