Maximum area of rectangle with fixed perimeter. How can you, with polynomial functions, determine the maximum area of a rectangle with a fixed perimeter.
Here's the exact problem—

You have 28 feet of rabbit-proof fencing to install around your vegetable garden. What are the dimensions of the garden with the largest area?

I've looked around this Stack Exchange and haven't found an answer to this sort of problem (I have, oddly, found a similar one for concave pentagons).
If you can't give me the exact answer, any hints to get the correct answer would be much appreciated.

Put the perimeter into the vertex formula.  
(Find the P=a+b equation and put it into the A=a*b equation.)  
The answer is the maximum point.
