Question 137333
The max area of a rectangle is always a square. So the sides should be 180/4.

Now, how do you find that out?
Let L be the length. 
We know the perimeter of a rectangle is 2*length + 2 * width.
{{{180 = 2L + 2W}}}
{{{90 - L = W }}}

Area = Length * width = {{{L*W}}}
{{{A = L * (90-L)}}}
{{{A = 90L - L^2}}}

You can plot that using your calculator or find the zeros and then know that the shape is such that halfway between the zeros is the max