SOLUTION: A rectangular plot of land is to be enclosed by fencing. One side is along a river and so needs no fence. If the total fencing available is 1800 meters, find the dimensions of the

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons -> SOLUTION: A rectangular plot of land is to be enclosed by fencing. One side is along a river and so needs no fence. If the total fencing available is 1800 meters, find the dimensions of the       Log On


   

Question 1084899: A rectangular plot of land is to be enclosed by fencing. One side is along a river and so needs no fence. If the total fencing available is 1800 meters, find the dimensions of the plot to have maximum area. (Assume that the length is greater than or equal to the width.)
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Dimensions x and y;
Let x be one of distances along the river.

Fence length, x%2B2y=1800

Area, A=xy


A=x%281800-x%29%2F2

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A is a parabola with vertex as a maximum. Find x in the exact middle of the zeros.

%281%2F2%29x%281800-x%29=0
x%281800-x%29=0
Roots are 0 and 1800.

highlight%28x=900%29, highlight%28y=450%29