The emblem of the International Congress of Mathematicians held in Beijing in 1998 was designed according to the Pythagorean square map written by Zhao Shuang, an ancient mathematician in China. It is a big square consisting of four congruent right-angled triangles and a small square in the middle (as shown in the figure). If the area of a large square is, the area of a small square is, the short right angle side of a right triangle is, and the long right angle side is, the value is (? )A. B. C. D. C