In a Suspension Bridge, the Shape of the Suspension Cables

Multiple Choice

In a suspension bridge, the shape of the suspension cables is parabolic. The bridge shown in the figure has towers that are 400 m apart, and the lowest point of the suspension cables is 100 m below the top of the towers. Find the equation of the parabolic part of the cables, placing the origin of the coordinate system at the lowest point of the cable. NOTE: This equation is used to find the length of the cable needed in the construction of the bridge.

A) x ² = 800y
B) x ² = 400y
C) x ² = -400y
D) x ² = 1,600y
E) y ² = 1,600x