The little maid's papa has taken two different-sized rectangular pieces of cardboard, and has clipped off a triangular piece from one of them, so that when it is suspended by a thread from the point A it hangs with the long side perfectly horizontal, as shown in the illustration. 
He has perplexed the child by asking her to find the point A on the other card, so as to produce a similar result when cut and suspended by a thread.
Of course, the point must not be found by trial clippings. 
A curious and pretty point is involved in this setting of the puzzle. 

Can you discover it?

See answer