Problem 2: Estimate the area under the graph of f(x) = 4 cos(x) from x = 0 to x = π/2. (Round the answer to four decimal places.)(a) Use four approximating rectangles and right endpoints.
My work and answer (which is wrong according to the site)
Delta x= Pi/2 / 4 = pi/8
R4= pi/8 (3.8+3.4+2.5+1.6)
(b) b) Use four approximating rectangles and left endpoints.
L4= pi/8 f(pi/8) + pi/8 f(pi/4) +pi/8 f(3pi/4)
L4= pi/8 (4 + 3.9 +3.3 + 2.7)
I made a graph so these values are my estimates