Chapter 7.4, Problem 12P

In Problems 3 to 12, find the average value of the function on the given interval. Use equation ( 4.8 ) if it applies. If an average value is zero, you may be able to decide this from a quick sketch which shows you that the areas above and below the $x$ axis are the same.

${\cos }^2\frac{7\pi x}{2}$ on $\left(0,\frac{8}{7}\right)$