3. Let f(t) = cos(t) - sin(t). For each a -/4, ) define Ra to be the region between the graph of f and the t-axis, and between the vertical lines t = -/4 and t = a. (Here we label the horizontal axis as the t-axis. ) (a) In the diagram below sketch the region Ra. Without using the fundamental theorem of calculus, determine whether the rate of change of the signed area of the region is positive for this value of a. Explain your answer in terms of how the signed area is changing at this point. f N (b) Find the maximum and minimum values of the rate of change of the signed area of Ra for a 4.5/3.