A farmer is fencing a rectangular area for cattle and uses a straight portion of a river as one side of the rectangle, as illustrated in the figure. Note that there is no fence along the river. If the farmer has 900 feet of fence, find the dimensions for the rectangular area that gives the maximum area for the cattle.
A rectangular area of land with a river on one long side of the rectangle and fencing on the other three sides. The short side of the rectangle is labeled x.