Attachment 27735f you can't read it, "A horizontal brige is in the shape of a parabolic arch. Given the information in the picture below, what is the height of the arch 2 feet from the shore?

Please help!!

Thank you

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- Mar 29th 2013, 12:33 PMBrendaBParabolic Arch
Attachment 27735f you can't read it, "A horizontal brige is in the shape of a parabolic arch. Given the information in the picture below, what is the height of the arch 2 feet from the shore?

Please help!!

Thank you - Mar 29th 2013, 01:24 PMHallsofIvyRe: Parabolic Arch
You can answer your question yourself with a little thought: Yes, setting up a coordinate system so that

**the center of the bridge is at the origin**, the parabola is of the form y= ax^2. When x= 10, at the shore, y= -10 so you must have -10= a(10^2)= -100a. Dividing both sides by -100, a= -1/10 so the equation is y= -x^2/10. Now, in that coordinate system, "2 feet from the shore" is x= 8 or x= -8.