\coordinate (O) at (0,0,0);
\pgfmathparse{3} \let\R\pgfmathresult;
\pgfmathparse{1.1} \let\t\pgfmathresult;

\coordinate (i) at (\R,0,0);
\coordinate (j) at (0,\R,0);
\coordinate (k) at (0,0,\R);



\draw[-latex] (O) -- (i);
\draw[-latex] (O) -- (j);
\draw[-latex] (O) -- (k);
\draw ($(O)!\t!(i)$) node {$x$};
\draw ($(O)!\t!(j)$) node {$y$};
\draw ($(O)!\t!(k)$) node {$z$};


\coordinate (P) at (0,2*\R,3*\R);

\draw[-latex] (O) -- (P);
\draw ($(O)!\t!(P)$) node {$P$};
