Question 1121553: Hello, I need help to solve this, but i'm not sure if my answer is right.
The height of a suspension cable above the roadway of a new suspension bridge, with two equally tall towers, is described by the equation
y = 0.05(x - 30)^2 + 6. In this equation, x represents the horizontal distance, in metres, from one tower to the other tower, and y represents the height, in metres, of the cable above the roadway.
h) If vertical cables are required every 6 m along the roadway, how much cable is needed for the entire bridge?
y = 0.05(6 - 30)^2 + 6.
y = 0.05(-24)^2 + 6
y = 0.05(576) + 6
y = 28.8 + 6
34.8m of cable for the entire bridge.
Is this correct? Thank you so much.
Answer by ikleyn(52803)   (Show Source):
You can put this solution on YOUR website! .
You calculated the length of ONLY ONE cable which is at the distance of 6 meters from the tower.
You need to calculate the corresponding lengths for EVERY cable.
The distance between the towers is 30 + 30 = 60 meters; hence, there are  = 9 cables, in all, of different lengths.
Make a sketch - it will help you a lot.
Also, as everybody who saw a suspension cable bridge (in a real life, in a photo, in a picture, in a video) knows
that the suspension cables are located/placed at both sides of the bridge.
So, when you calculate the total length of the cables at one side of the bridge, you must then DOUBLE it (!)
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