An engineer designed a suspension bridge with three hanging cables, with the end of each cable attached to a tower. He defined cable AB by the function f(x) = 0.1(x+11)^2+5 The bridge has a clearance of 24ft above the water's surface. Knowing that the width of each tower is 2 ft, what is the height of each tower?
(Assume that the tower at point B is centered on the y-axis and that the cables are attached to the ends of the tower.)