Suppose you have to use exactly 200 m of fencing to make either one square enclosure
or two separate square enclosures of any sizes you wish.
What plan gives you the least area? the greatest area?
Let the two squares have sides x
The total area of the two squares is:
The two squares will have a total perimeter of
Substituting into the area function:
So, we have:
the graph is concave upward.
Hence, with two 25-meter squares, we have minimum
Any other value of x
will produce a larger area.
So at the very extreme, we can let
and have one square with a maximum