Solution: Let two right-angled sides of each right-angled triangle be x, y (x >; y)

Then: x+y=5 ①

X 2 +y 2 = 13 ②

From ①: x 2 +2xy+y 2 =25 ③

③-① Get: 2xy= 12？

∫ The sum of the areas of four right triangles is 2xy.

∴ The area of Little Square = 13- 12 = 1

A: The area of a small square is1;

(2) as shown in figure