Unless specified, all approximating rectangles are assumed to have the same width. Evaluate the upper and lower sums for f(x) = 1 + cos(x/2), ???? x ????, with n = 3, 4, and 6. Illustrate each case with a sketch similar to the figure shown below. (Round your answers to two decimal places.) Figure: The x y-coordinate plane is given. A curve and two sets of 5 rectangles are graphed. The x-axis from x = a to x = b is divided into 5 subregions, each of which becomes a shared base for rectangles of width (b a)/5. - The curve enters the window in the first quadrant above x = a, goes down and right, changes direction, goes up and right, changes direction, goes down and right, and exits the window in the first quadrant above x = b. - The first set of 5 rectangles extends up and intersects the curve at the higher value within each subregion. - The second set of 5 rectangles extends up and intersects the curve at the lower value within each subregion. n = 3, 4, 6: upper sum = lower sum =