3d plots in tikz

To plot a 3d plot with latex in tikz you should use the tikz3dplot package:

\usepackage{tikz-3dplot}

 you can define the coordinate system by using:

\tdplotsetmaincoords{70}{110}

after that you can use 3d coordinate definitions:

\begin{tikzpicture}[tdplot_main_coords]
\draw[thick,->] (0,0,0) -- (1,0,0) node[anchor=north east]{$x$};
\draw[thick,->] (0,0,0) -- (0,1,0) node[anchor=north west]{$y$};
\draw[thick,->] (0,0,0) -- (0,0,1) node[anchor=south]{$z$};
\end{tikzpicture}