A farmer has 150 m of fencing and wants to make a rectangular enclosure next to a straight farm wall so that the wall forms one side of the rectangle. The farmer uses no fencing along the wall. The three sides to be fenced are two equal widths and one length.
(a)If the width perpendicular to the wall is w metres and the length along the wall is L metres, write an equation connecting w, L and the total fencing used.(1)
(b)Express the area A of the enclosure in terms of w only, and simplify.(2)
(c)Using your formula from part (b), work out the area A for w = 30, w = 35, w = 37.5 and w = 40. Use your results to state which of these widths gives the largest enclosure area.(3)
(Total for Question 4 is 6 marks)