6. Consider the curve f(x) = 3 cos and the portion of its graph that lies in the first quadrant between the y-axis and the first positive value of x for which f(x) = 0. Let R denote the region bounded by this portion of f, the x-axis, and the y-axis. Assume that x and y are each measured in feet. a. Picture the coordinate axes rotated 90 degrees clockwise so that the positive x-axis points straight down, and the positive y-axis points to the right. Suppose that Ris rotated about the x axis to form a solid of revolution, and we consider this solid as a storage tank. Suppose that the resulting tank is filled to a depth of 1.5 feet with water weighing 62.4 pounds per cubic foot. Find the amount of work required to lower the water in the tank until it is 0.5 feet deep, by pumping the water to the top of the tank