According to Pythagorean theorem, the hypotenuse of a triangle, that is, the side length of a big square, is 5, that is, the area of a big square is 5 times 5 to 25 square centimeters; The side length of a small square is the long right angle side of a triangle minus the short right angle side: 4-3= 1, so the area of a small square is 1 times 1 to 1 square centimeter.