So I'm trying to solve this by using Stokes' :$F(x,y,z)=2y\cos(z)i+e^x\sin(z)j+xe^yk$, where $S$ is the hemisphere $x^2+y^2+z^2=9$ oriented upward, $z$ larger than or equal to $0$. I do this by letting $r(t)=3\cos ti+3\sin tj+0k$ , and then evaluate integral $F\cdot dr$ from $0$ to $2\pi$. Lo and behold and I get $-18\pi$. Now, that ain't right. What am I doing wrong?