\tdplotsetmaincoords{77}{-8}% \begin{tikzpicture}[tdplot_main_coords] x={(2 cm, 2 cm)},% y={(2 cm, 2 cm)},% z={(2 cm, 2 cm)}% ]% \draw [->] (0,0,0) -- (1,0,0) node[below] {$x_1$};% \draw [->] (0,0,0) -- (0,0,1) node[left] {$x_2$};% \draw [->] (0,0,0) -- (0,1,0) node[left] {$x_3$};% \end{tikzpicture}%