<PRE><B>Question 1033413</B>
The maximum area for a rectangle is when it is a square.  This can be proven a variety of ways, but I will use that.
7.5 m on a side
7.5^2=56.25 sq m.  B

Let x equal a side of a rectangle and y equal the other side
P=2x+2y
(P-2y)/2=x
area ix xy=y(P-2y)/2=[Py-2y^2]/2
The maximum of this quadratic (which has a vertex at highest point, because the y^2 coefficient is negative is at (1/2)(P-4y).
Set that equal to 0, multiply by 2 and move terms, and 4y must equal P.
y=(1/4)P, and that is a square.
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