The pythagorean is a^2 + b^2 = c^2, with a and b as its sides and c as its hypotenuse (longest side). In this case, a and b are 6 and x and the hypotenuse is 20. The equation is 6^2 + x^2 = 20^2
36 + x^2 = 400
x^2 = 400 - 36 = 364
x = sqrt 364
x = 2sqrt91 or 19.08
