SOLUTION: Please help me to solve this word problem. A portion of a roller coaster is supported by two steel beams. A cable runs from the top of each beam to the bottom of the other. if o

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Question 139624: Please help me to solve this word problem.
A portion of a roller coaster is supported by two steel beams. A cable runs from the top of each beam to the bottom of the other. if one steel beam is 40 feet tall and the other beam is 30 feet tall how high above teh ground do the cables intersect.
I have drawn a picture and added in the information from the problem and proved that the triangles fromed were similar, but i dont know what to use to set up the proportion please help.
Answer by scott8148(6628) (Show Source):
You can put this solution on YOUR website!
picture both beams standing on the x-axis, with the 40 footer running up the y-axis
__ and the 30 footer some distance d in the positive x direction

let d="distance between beams" __ y=mx+b

1st cable __ y=(-40/d)x+40

2nd cable __ y=(30/d)x+0 __ yd/30=x

substituting __ y=(-40/d)(yd/30)+40 __ y=(-4y/3)+40 __ 7y/3=40 __ 7y=120 __ y=120/7 __ a little over 17 ft.