2. (a) Apply both the first and second derivative tests to show that f(x) = sin r has a relative minimum at x = 0. Justify your answer by using graph. (b) A rectangular area of 3200 ft is to be fenced off. Two opposite sides will use fencing costing 2 dollar per foot and the remaining sides will use fencing costing 3 dollar per foot. Find the dimensions of the rectangle of least cost. %3D