4. In this problem you will use Riemann sums to find the length of a curve y = f(r) between r = a and r = b (assuming f(r) is differentiable). (a) Let P = {To, T1, ..., n} be a partition of a, b . Over each subinterval of the partition, approximate the curvey = f(r) with straight line segments, L;, connecting (Ti-1, f(Ti-1)) and (T;, f(T;)). Draw a picture of this setup. (b) Assuming that f(r) is differentiable, use the mean value theorem to find points x* in [Ti _1, I;] with f'(x;) = (@)-f(2 1) Ari