Chapter 6.5, Problem 31E

Golden Gate cables The profile of the cables on a suspension bridge may be modeled by a parabola. The central span of the Golden Gate Bridge (see figure) is 1280 m long and 152 m high. The parabola y = 0.00037x² gives a good fit to the shape of the cables, where |x| ≤ 640, and x and y are measured in meters. Approximate the length of the cables that stretch between the tops of the two towers.