Nech� $\Bbb F = (P,Q R)$, $z=h(x,y)$ pro $(x,y) \in D$
popisuje plochu $S$. Doka�te, �e
$$
\int \! \BBb F {d \vec S} = 
\int _{D} \Left ( 
-P \cdot \frac {\partial z} {\partial x}
-Q \cdot \frac {\partial z} {\partial y}
+R  \Right ) \mbox {d}x \mbox {d}y \quad .
$$

