%\documentclass{standalone} Gia na to kano se eikona bazo auto na to xo mono toy se arxeio 
\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\draw[<->] (-4,0) -- (4,0) node[right] {$x$};  %komvos node tou x
\draw[<->] (0,-1.5) -- (0,1.5) node[above] {$y$};
\draw[scale=1, domain=-4:4, smooth, variable=\x, red] %klimaka, perioxh sxediashw
	plot({\x}, {sin(\x r)}) node[right] {$y=\sin x$};
\draw[scale=1, domain=-4:4, smooth, variable=\x, blue]
	plot({\x}, {cos(\x r)}) node[above right] {$y=cos x$};
\end{tikzpicture}
\end{document}
