Describe Testo here. <<latex(\usepackage{dsfont} % $$\mathds{R}$$)>> <<latex($$\sigma$$)>>

\begin{equation}
x=R\frac{\beta\theta}{\sqrt{\alpha\beta}}\cos{(\alpha\phi)}
\end{equation}

\begin{eqnarray}
y & = & R\frac{\alpha\phi}{\sqrt{\alpha\beta}} \\
\alpha & = & \frac{2\arccos{c}}{\pi} \\
\beta & = & \frac{\alpha}{2p}
\end{eqnarray}