A trapezoid is divided into four triangles by its diagonals. Suppose the top and bottom triangles have areas of A and B. Express the AREA of the trapezoid in terms of A and B.

Here is a picture of the problem:

http://i216.photobucket.com/albums/c...hchallenge.jpg

I know the solution already, but just want to see if there's a much simpler way.