how do I solve (b)

Exercise 2.2 Find the area bounded by the r-axis, the y-axis, and the graph of the function y = f(x) = 1 -@. (See Figure 2.11.) (a) By using your knowledge about the area of a triangular region. (b) By setting up the problem as a Riemann sum, i.e., as a sum of the areas of N rectangular strips, using the appropriate summation formula, and letting the number of strips (/V) get larger and larger to arrive at the result. Show that your answer in (b) is then identical to the answer in (a). The point of this exercise is to practice setting up and computing Riemann sum