The perimeter of rectangular is
.
Consider length of rectangular is
and width of the rectangular is
,then perimeter of rectangular is
.
But one side width has covered by highway,hence the perimeter is
.
The area of rectangle
is
.
if
,
.
Substitute
in the equation
.

.
The area of rectangle is
.
Find the maximum area of rectangle.
\The maximum area of rectangle occurs when the length is maximum.
\
is the form of general quadratic equation.
Therefore
and
.
The maximum area occurs at
.

The maximum length is
.
Substitute
in the function
to get the maximum area.



The maximum area is
.
The maximum area is
.