\setlength{\unitlength}{1cm}
\linethickness{1.5pt}
\centering
\begin{Picture}(-7,-4.5)(7,4.5)
{\makenolabels
\changereferencesystem(0,0)(\numberHALFPI,0)(0,1)
\cartesiangrid(-4,-4)(4,4)
\highestlabel{$2\pi$}
\printylabels{-4}{1}{4}
\printxlabel{-4}{-2\pi}
\printxlabel{-2}{-\pi}
\printxlabel{2}{\pi}
\printxlabel{4}{2\pi}}
\pictcolor{red}
\PlotFunction[16]{\COSfunction}{-\numberTWOPI}{\numberTWOPI}
\pictcolor{blue}
\PlotFunction[16]{\SINfunction}{-\numberTWOPI}{\numberTWOPI}
\pictcolor{magenta}
\PlotFunction[6]{\TANfunction}{-1.3258}{1.3258}
\end{Picture}
