Calculate $\int\int_sf(x,y,z)dS$ for $x^2+y^2=9$, $0<z<6$; $f(x,y,z)=e^{-z}$
I am completely confused on this. I know I can parameterize $x^2+y^2=9$ into...
$x(r,\theta)=rcos\theta$ and $y(r,\theta)=rsin\theta$
however past that I don't have a clue. There isn't any explicitly stated relationships between x, y, and z such that I can parameterize z as well. I'm not so much looking for an answer as I am looking for a way to look at this so that I can figure it out. Thank you for the help in advanced.