



 
Hi Lanny, I assume from the information you gave, the trough looks like this:
The volume of the triangular prism is area of the triangle x the length or V=1/2 bhl. Notice that the base of the triangle is twice as big as the height so we could simplify the formula for volume to V=1/2 (2 h)hl=h^{2}l. Also remember that l is constant when the trough is filling so we can substitute 10 feet right into the formula so V=5h^{2}. Lastly, use implicit differentiation to solve for your rate of change but don't forget to make sure all of the units of measurement are the same. Hope this helps, Janice  


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