Spo�t�te
$$
\int \! ({x}^{2}+{y}^{2}+{z}^{2} )
{d \varphi}=2\,\pi \,\sqrt {
{a}^{2}+{b}^{2}}\left ({a}^{2}+{\frac {4\,{\pi }^{2
}{b}^{2}}{3}}\right ) \quad ,
$$
kde $\varphi (t) := (a\cos(t),a\sin(t),bt)$, $t \in [0,2\pi]$
je k�ivka naz�van� �roubovnice.


