Chapter 4.5, Problem 96PE

For Exercises 95-96, find the average rate of change on the given interval. Give the exact value and an approximation to $4$ decimal places. Verify that your results are reasonable by comparing the results to the slopes of the lines given in the graph.

$f\left(x\right)=\cos x$

a. $\left[0,\frac{\pi }{6}\right]$

b. $\left[\frac{\pi }{6},\frac{\pi }{3}\right]$

c. $\left[\frac{\pi }{3},\frac{\pi }{2}\right]$