Problem Solving

Problem Solving

7. A 10ft high truck passes under a parabolic arch. Find the maximum distance x that the side of the truck can be from the center of the road.



    First set the reference axes at a convenient location. I chose the top of the arch.

    Next write the equation for the parabola. Use the point (-18, -18)

                x2 = 4py

                   (-18)2 = 4p(-18)            p = -4.5

                     x2 = -18y

          Now reread the problem. What is the critical point? When y = -8.

            So…    x2 = -18(-8)

                Then        x= 12ft

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