F\left( z \right) = P\left( {\tan Y \leqslant z} \right) = P\left( {\bigcup\limits_{k \in \mathbb{Z}} {\tan Y \leqslant z \cap Y \in \left\langle {k\pi - \frac{\pi }
{2},k\pi + \frac{\pi }
{2}} \right\rangle } } \right) =