[Tex/LaTex] Triangle with text

Question

Can someone help me draw a equilateral triangle with numbers 1, 2, 3 at each interior angle of it? Also I need to equate a letter with that triangle; namely F = graph. Thanks in advance.

Answer 1

Without any fancy techniques:

\documentclass[tikz,border=5mm]{standalone}
\usetikzlibrary{positioning}

\begin{document}
\begin{tikzpicture}
\coordinate (a) at (0,0);
\coordinate (b) at (2cm,0);
\coordinate (c) at (60:2cm);
\node[above left = 0.65cm and 0cm of a] {$F=$};   %% change distances suitably
%
\draw (a) -- (b) -- (c) -- cycle;
\path[clip] (a) -- (b) -- (c) -- cycle;
\node[circle,draw,minimum size=0.4cm] at (a) {};
\node[font=\tiny,inner sep=0pt] at (30:0.3cm) {$1$};
\node[circle,draw,minimum size=0.4cm] at (b) (circa) {}
node[font=\tiny,inner sep=0pt,above left = 0.1cm and 0.2cm of b]  {$2$};
\node[circle,draw,minimum size=0.4cm] at (c) (circa) {} 
node[font=\tiny,inner sep=0pt,below = 0.25cm of c] {$3$};
\end{tikzpicture}

\end{document}

Adopting the code from Torbjorn's answer:

\documentclass[border=5mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric,positioning}

\tikzset{
    buffer/.style={
        draw,
        name=s,
        shape border rotate=0,
        regular polygon,
        regular polygon sides=3,        
        node distance=2cm,
        minimum height=4em
    }
}

\begin{document}
\begin{tikzpicture}
\node[buffer,label={left:$F=\,$}]{};
\clip (s.corner 1) -- (s.corner 2) -- (s.corner 3) --cycle;
\draw (s.corner 1) circle (0.2cm) node[font=\tiny,inner sep=0pt,below = 0.25cm of s.corner 1] {$3$};
\draw (s.corner 2) circle (0.2cm) node[font=\tiny,inner sep=0pt,,above right = 0.1cm and 0.2cm of s.corner 2] {$1$};
\draw (s.corner 3) circle (0.2cm) node[font=\tiny,inner sep=0pt,,above left = 0.1cm and 0.2cm of s.corner 3] {$2$};
\end{tikzpicture}
\end{document}