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put this solution on YOUR website!the maximum area within a rectangle is a rectangle in the form of a square
thus l=w and 2l+2w=400 2l+2l=400 or 4l=100 & 2w+2w=400 or 4w=400 or w=100
thus a square of 100 by 100 will provide the maximum area for a fence of 400
feet of lumber.
thus the area within this square of 100 by 100 feet is 100*100=10000 sq feet.