Farmer Joe wants to fence in a rectangular area that has one side bordered by a stream. If he has 80 meters of fencing, what are the dimensions and the maximum area he can enclose? The area of the fenced area can be found using the formula A = lw where l represents the length and w represents the width. The bottom is the stream, the top is equal to 80-2x, and the two sides are equal to x. This is quadratics as well.