What is the value of S4 for \sum_(n=1)^(\infty ) (1)/(4)(-(1)/(3))^(n-1)

Use the formulas a = x 2 – y 2, b = 2xy, c = x 2 + y 2 to answer this question. one leg of a right triangle has length 11 and all sides are whole numbers. find the lengths of the other two sides. the other leg = a0 and the hypotenuse = a1