2. (6 points) All parts of this problem refer to the region under the graph of f (x) = 12, above the x-axis, and between x = 0 and a = 6. Denote this region by R. (a) Sketch the region R described above. Then, represent the area of the sketched region R as a definite integral. [Note: Do not calculate the integral.] (b) Approximate (estimate) the area of the above region R using 3 rectangles (n = 3) and left endpoints. Sketch the rectangles and show all work. (c) Approximate the area of the above region R using 3 rectangles (n = 3) and right endpoints. Sketch the rectangles and show all work