A farmer has \( 1,568 \) feet of fencing available to enclose a rectangular area bordering a river. No fencing is required along the river. Let \( x \) represent the length of the side of the rectangular enclosure that is perpendicular to the river. Complete parts a through c.

a. Create a function, \( A ( x ) \) , that describes the total area of the rectangular enclosure as a function of \( x \) , where \( x \) is the length of the rectangular enclosure that is perpendicular to the river. A(X)=______?

b. Find the dimensions of the fence that will maximize the area. The length of the side of the rectangle perpendicular to the river is _____and the length of the side of the rectangle parallel to the river is _____