\documentclass{article}
\usepackage{pstricks}
\usepackage{pst-plot}

\parindent=0pt
\pagestyle{empty}
\begin{document}

\begin{center}
\psset{xunit=0.03cm,yunit=1.5cm}
\begin{pspicture}(0,-2.5)(420,2.5)
\psaxes[Dx=30]{->}(0,0)(0,-2.25)(400,2.25)
\uput[-90](400,0){$\alpha$}\uput[180](0,2.2){$f(\alpha)$}
\psplot[linewidth=2pt,linecolor=green,linestyle=dotted]{0}{390}{x sin}
\psplot[linewidth=1pt,linecolor=blue,linestyle=dashed]{0}{390}{x 2 mul 30 sub sin neg}
\psplot[linewidth=1pt,linecolor=red]{0}{390}{x 2 mul 30 sub sin neg x sin add}
\end{pspicture}
\end{center}

\end{document}
