f(x)=2 cos(x), 0 x. 3 4 evaluate the left Riemann sum with n = 6, taking the sample points to be left endpoints. (Round your answer to six decimal places.) What does the Riemann sum represent? The Riemann sum represents the net area of the rectangles with respect to the Select- Illustrate with a diagram. y 2 0-2 y 2 y 2 x 3r 5 3 3 5 3 8 2 8 8 8 4 y 2 O-2/ 4 5 co x E