estion 1 of 11 > A rectangular bird sanctuary is being created with one side along a straight riverbank. The remaining three sides are to be enclosed with a protective fence. If there are 4 km of fence available, find the dimension of the rectangle to maximize the area of the sanctuary. (Give your answer as a whole or exact number.) length of fencing perpendicular to the riverbank: km length of fencing parallel to the riverbank: km