The side length of the two right angles is and should be 14cm, which is the pre-holiday diagram of the first section of exploring Pythagorean theorem in section 2.6 of eighth grade mathematics of Zhejiang Education Press. The area of a big square is 100 cm 2, so the side length is 10CM, that is, the hypotenuse length of a right triangle is 10cm, and the side lengths of two right-angled sides are 14cm. According to Pythagorean theorem, the right-angled sides are 6cm and 8cm respectively, so the area of right-angled triangle is 24cm^2, and the area of small square is = 654 cm.