



 
Hi Jim. Draw this on graph paper, with the xaxis representing the road and the origin the center of the road. If you do this, you find that you have a parabola with Y intercept at (0,18), and x intercepts at (+/20,0). You will need to estimate the curvature between the intercepts for now. That's the bridge overhead. Now draw a rectangle with corners at (+/7.5,15) and (+/7.5,0). That's the trailer. You are interested in knowing if the corners whack into the parabola or not. The easiest way is to first come up with the equation for the parabola with these intercepts, then substitute x = +/7.5 into it. If the value for y is greater than 15, then you should be safe, otherwise the trailer hits the bridge. Hope this helps,  


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