Select the third function, y = 2 cos(x),

and set the interval to [−4.01, 4.01].

(a) With 10 rectangles using left endpoints, how many rectangles are contributing negative area values to the estimated net area?

How many are positive?

(b) What is the error when using midpoints with 10 subintervals? (Do not round your answer.)

What is the ratio of the left-endpoint approximation error to the midpoint error? (Round your answer to two decimal places.)

(c) Of the available choices, how many subintervals are required to give a midpoint approximation accurate to 2 decimal places?