SOLUTION: This is a quadratic word problem. A concrete bridge has an arc shaped like a parabola underneath. The top of the bridge is 4m from the surface of the water and the arch (at the

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Question 888771: This is a quadratic word problem.
A concrete bridge has an arc shaped like a parabola underneath. The top of the bridge is 4m from the surface of the water and the arch (at the center) is 3m from the water. The width of the arc at water level is 10m.
What is the equation of the arc?
How thick is the concrete 2 meters from the center of the bridge?
I do not understand where these measurements are placed so I can not create an equation. A quick reply would be great as I have a summative tomorrow.
Thank you.

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
The top of the bridge and the top of the "arch" underneath is the difference 4-3=1. The thickness of this bridge must be 1 meters. This means, the thickness of the concrete. The width of the arc at the water level being 10 meters is ambiguous; but it was likely intended to mean "from where the arc meets the water at one end to where the arc meets the water at the other end".

The problem seems to describe two parabolas. The arc underneath being height 3 m and "width" 10 meters; and the "bridge" above being height 4 m of of "width" 10%2B2%2A1 m.

You can take your origin wherever you find convenient.

You would find standard form to be best to use. Your "a" valuse would be negative quantities, since each vertex will be a maximum point of each parabola.
Refers to y=a%28x-h%29%5E2%2Bk.