<image>(2014 Autumn • Mid-term exam in Anlu City) As shown in the figure, the side length of the square ABCD is 4. A sufficiently large right-angled set square is placed with its right angle vertex at point A. The two perpendicular sides of the set square intersect CD at point F, and the extension line of CB at point E. The area of quadrilateral AECF is _____.