\documentclass{standalone}

\usepackage{tikz}
\usetikzlibrary{calc}

\begin{document}
   \begin{tikzpicture}
       %Define coordinates
       \coordinate (A) at (1,2);
       \coordinate (B) at (-3,1);
       \coordinate (C) at (2,-3);
       
       \coordinate (M) at ($1/3*(A)+1/3*(B)+1/3*(C)$);
       
       %%draw the triangle
       \draw (A) -- (B) -- (C) -- cycle;
       
       %Draw nodes with titles
       \filldraw (A) circle(1pt) node[right] {$A$};
       \filldraw (B) circle(1pt) node[left]  {$B$};
       \filldraw (C) circle(1pt) node[anchor=north west] {$C$};
       
       \filldraw (M) circle(1pt) node[anchor=west] {$M$};
       
   \end{tikzpicture}
\end{document}