Исходники иллюстрации

\documentclass[tikz]{standalone}\input{pre.tex}\begin{document}\begin{tikzpicture}
        \coordinate (A) at (0,0);
        \coordinate (B) at (0.5,-2);
        \coordinate (C) at (4,0);
        \draw[fill=black] (C) circle (1pt) node [right] {$m_i$};
        \draw[fill=black] (0,0) circle (1pt) node[left] {$O'$}; 
        \draw[fill=black] (0.5,-2) circle (1pt) node[left] {$O$}; 

        \draw[->, >=latex] (A) -- node [above] {$\vec{r}\zi$} (C);
        \draw[->, >=latex] (B) -- node [above] {$\vec{r}_i$}  (C);
        \draw[->, >=latex] (B) -- node [left] {$\vec{\rho}$}  (A);
    
\end{tikzpicture}\end{document}