What is the length (side parallel to the river) and width (sides perpendicular to the river) that creates the enclosure with the most area?

Question

You are a llama farmer, and you must create a new enclosure for your llamas. You have recently purchased 16001600 meters of fencing, and you wish to create the largest enclosure possible to keep your llamas happy. One side of your property borders a large river, that the llamas are not able to cross, so you decide to use this as part of the enclosure border (because of the river you do not need fencing for this side of the enclosure). You decide to complete the enclosure with three straight sides of fencing. What is the length (side parallel to the river) and width (sides perpendicular to the river) that creates the enclosure with the most area?

Length:  meters

Width:  meters

Answer 1