We can model the function in that interval as a straight line of negative slope.
We have then that the average rate of change in that interval is given by:
r = (y2-y1) / (x2-x1)
Substituting values:
r = (- 4-4) / (2π-π)
Rewriting we have:
r = -8 / π
Answer:
the rate of change from x = π to x = 2π is:
r = -8 / π
