Chapter 15.8, Problem 11ES

Use Stokes’s Theorem to evaluate ${\displaystyle \underset{C}{\oint }\text{F}.dr.}$

$\text{F(}x,y,z)=(x-y)\text{i}+(y-z)\text{j}-(z-x\text{)k;}C$ is the circle in the plane $x^2+y^2=a^2$ in the xy-plane with counterclockwise orientation looking down the positive z-axis.