a) The rectangles in the graph below illustrate a ? X Riemann sum for f(x) = 2 sin a on the interval [0, 7]. The value of this Riemann sum is 2nt A 1 -pi/2 pi/2 Pi 3pi/2 -2 -3 -4 -5 Left endpoint Riemann sum for y = 2 sin x on [0, 7b) The rectangles in the graph below illustrate a 5 The value of this Riemann sum is _ . v (9 Riemann sum for f(a:) = 2 sins: on the interval [0, 1r]. Right endpoint Riemann sum for y = 2 sin an on [0, 7r]