Let A be the area if the region in the first quadrant under the graph of y = cos(x) and above the line y = k for 0 k 1. Determine A in terms of k....

Let A be the area if the region in the first quadrant under the graph of y = cos(x) and above the line y = k for 0 < k < 1.a. Determine A in terms of k.b. Determine the value of A when k = 1/2c. If the line y = k is moving upward at a rate of 1/pi units per minute, at what rate is the area A changing when k = 1/2?