Algebra problem (10) Below is pictured a rectangular triangle with sides a,b and c. Prove the formula for the area A. The proof is found below. At ...1) of the solution: (a + b)2 = a2 + 2ab + b2 so also: (a2 + b2)2 = a4 + 2a2b2 + b4 At ...2) of the solution: a2 - b2 = (a - b)(a + b) so also: a4 - b2 = (a2 - b)(a2 + b) Don't forget Pythagoras. Where in the proof is his rule applied?