\documentclass{minimal}
\usepackage{pstricks,pst-plot}
\usepackage{xepersian}
\settextfont{XB Zar}
\begin{document}
\begin{center}
\begin{LTR}
\psset{yunit=4cm,xunit=0.75cm}
\begin{pspicture}(-10,-1.5)(8,1)
\psaxes[axesstyle=frame,Ox=-8,Oy=-1,Dx=2,Dy=0.5,labelsep=1pt](-8,-1)(8,1)
\psplot[linecolor=green,linestyle=dashed,plotstyle=curve]{-6.5}{6.5}{x  RadtoDeg sin}
\psplot[linecolor=blue,plotstyle=curve]{-6.5}{6.5}{x  RadtoDeg cos}
\uput[0](5.15,0){$\sin(x)$ سینوس}
\uput[0](4.15,0.75){$\cos(y)$ کسینوس}
\uput[-90](0,-1.1){XLabel}
\rput{90}(-9.5,0){YLabel}
\end{pspicture}
\end{LTR}
\end{center}
\end{document}