Desenhe setas nos lados do triângulo

Question

MWE:

\documentclass[12pt]{article}
\usepackage{pgf}
\usepackage{tikz}
\usepackage{pgfplots}
\begin{document}
    \begin{tikzpicture}
    \draw [line width=1pt] (0,5)-- (0,0);
    \draw [line width=1pt] (5,0)-- (0,5);
    \draw [line width=1pt] (0,0)-- (5,0);
    \draw [fill=black] (0,5) circle (1.5pt);
    \draw[color=black] (0.0,5.5) node {$A$};
    \draw [fill=black] (0,0) circle (1.5pt);
    \draw[color=black] (0.0,-0.5) node {$B$};
    \draw [fill=black] (5,0) circle (1.5pt);
    \draw[color=black] (5.0,-0.5) node {$C$};
    \end{tikzpicture}
\end{document}

Pergunta:

Como posso desenhar uma seta de direção em cada linha do triângulo? (todos os estilos possíveis de setas)

Answer 1

Talvez eu tenha interpretado mal a pergunta, mas se você quiser variar o tipo de seta, pode usar

\documentclass[12pt]{article} 
\usepackage{tikz} 
\usetikzlibrary{decorations.markings}
\begin{document}
% based on https://tex.stackexchange.com/a/39282/121799
\tikzset{->-/.style n args={2}{decoration={
  markings,
  mark=at position #1 with {\arrow{#2}}},postaction={decorate}}}
\begin{tikzpicture}[bullet/.style={circle,inner sep=1.5pt,fill}] 
 \path  (0,5) node[bullet,label=above:$A$](A){}
  (0,0) node[bullet,label=below:$B$](B) {}
  (5,0) node[bullet,label=below:$C$](C) {};
  \foreach \X/\Arrow [remember=\X as \LastX (initially C)]in
  {A/latex,B/stealth,C/>}
  {\draw[line width=1pt,->-={0.5}{\Arrow}] (\LastX) -- (\X);}
\end{tikzpicture} 
\end{document}

Quanto ao seu comentário: isso desenha três triângulos. É isso que você está procurando?

\documentclass[12pt]{article} 
\usepackage{tikz} 
\usetikzlibrary{decorations.markings}
\begin{document}
% based on https://tex.stackexchange.com/a/39282/121799
\tikzset{->-/.style n args={2}{decoration={
  markings,
  mark=at position #1 with {\arrow[line width=1pt]{#2}}},postaction={decorate}}}
\begin{tikzpicture}[bullet/.style={circle,inner sep=1.5pt,fill}] 
 \begin{scope}
  \path  (0,5) node[bullet,label=above:$A$](A){}
   (0,0) node[bullet,label=below:$B$](B) {}
   (5,0) node[bullet,label=below:$C$](C) {};
   \foreach \X [remember=\X as \LastX (initially C)] in  {A,B,C}
   {\draw[line width=1pt,->-={0.5}{latex}] (\LastX) -- (\X);}
  \end{scope} 
 \begin{scope}[xshift=6cm]
  \path  (0,5) node[bullet,label=above:$A$](A'){}
   (0,0) node[bullet,label=below:$B$](B') {}
   (5,0) node[bullet,label=below:$C$](C') {};
   \foreach \X [remember=\X as \LastX (initially C')]in  {A',B',C'}
   {\draw[line width=1pt,->-={0.5}{stealth}] (\LastX) -- (\X);}
  \end{scope} 
  \begin{scope}[yshift=-6.6cm]
  \path  (0,5) node[bullet,label=above:$A$](A''){}
   (0,0) node[bullet,label=below:$B$](B'') {}
   (5,0) node[bullet,label=below:$C$](C'') {};
   \foreach \X [remember=\X as \LastX (initially C'')]in  {A'',B'',C''}
   {\draw[line width=1pt,->-={0.5}{>}] (\LastX) -- (\X);}
  \end{scope} 
\end{tikzpicture} 
\end{document}

Answer 2

UsandoTikZ: Como desenhar uma seta no meio da linha?

%\documentclass[border=2mm]{standalone}
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{decorations.markings}
\begin{document}
\begin{tikzpicture}

    \draw [fill=black] (0,5) circle (1.5pt);
    \draw[color=black] (0.0,5.5) node {$A$};
    \draw [fill=black] (0,0) circle (1.5pt);
    \draw[color=black] (0.0,-0.5) node {$B$};
    \draw [fill=black] (5,0) circle (1.5pt);
    \draw[color=black] (5.0,-0.5) node {$C$};

\begin{scope}[very thick,decoration={
    markings,
    mark=at position 0.5 with {\arrow{>}}}
    ] 
    \draw [line width=1pt,postaction={decorate}] (0,5)-- (0,0);
    \draw [line width=1pt,postaction={decorate}] (5,0)-- (0,5);
    \draw [line width=1pt,postaction={decorate}] (0,0)-- (5,0);
\end{scope}
\end{tikzpicture}
\end{document}