If the two right angles of a right triangle are A and B and the hypotenuse is C, then A 2+B 2 = C 2.

This paper introduces a proof method: make three triangles with side lengths of A, B and C respectively, and put them together as shown in the figure, so that H, C and B are in a straight line, connecting BF and CD. Crossing C is CL⊥DE, crossing AB is at point M, crossing DE is at point L af = ac, AB = AD, ∫. The area of GAD is equal to half the area of rectangular ADLM, and the area of rectangular ADLM is =. Similarly, it can be proved that the area of the rectangle MLEB =. ∫ The area of square ADEB = the area of rectangular ADLM+the area of rectangular MLEB ∴ is A 2; +b^2； =c^2。