A rectangular garden is to be fenced using 40 metres of fencing along three sides, with an existing brick wall forming the fourth side. What is the maximum possible area of the garden?
Answer and explanation
Correct answer: B.
- Step 1: Let be the width of the two sides perpendicular to the wall. The length along the wall is . Step 2. Area . Differentiating and setting to zero: . The maximum area is . **Answer: . Why not the others:** assumes a square with four sides ( with perimeter 40); assumes requiring 60 m of fencing.
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