TikZ-PGF Triangles – Drawing Triangles with Different Directions and Bold Arrows

Question

I know that a triangle can be drawn like this:

\documentclass[12pt, border=5mm]{standalone}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\draw (0,0) node[anchor=north]{$A$}
  -- (4,0) node[anchor=north]{$C$}
  -- (4,4) node[anchor=south]{$B$}
  -- cycle;
\end{tikzpicture}
\end{document}

But I do not know how to draw these different orientations of a triangle:

Could anyone help me in this please?

Answer 1

If this is an option for you you can work around it with an arrow as a node:

Since this answer contains a mistake (nesting tikz enviroment) and there was a follow up question you can find an improved version here.

\documentclass[border=0.5cm]{standalone}
 
\usepackage{tikz}
 
\newcommand{\arrowL}{
\tikz \draw[latex-] (0,0) -- (0.1,0);
}
\newcommand{\arrowR}{
\tikz \draw[-latex] (0,0) -- (0.1,0);
}
 
\begin{document} 
\begin{tikzpicture}
%   Triangle 1
\node at (2,-1) {triangle 1};
\draw (0,0)--(4,0) node[sloped,pos=0.5]{};
\draw (4,0)--(4,4) node[sloped,pos=0.5]{\arrowR};
\draw (0,0)--(4,4) node[sloped,pos=0.5]{\arrowL};
\end{tikzpicture}
\begin{tikzpicture}
%Triangle 2
\node at (2,-1) {triangle 2};
\draw (0,0)--(4,0) node[sloped,pos=0.5]{};
\draw (4,0)--(4,4) node[sloped,pos=0.5]{\arrowR};
\draw (0,0)--(4,4) node[sloped,pos=0.5]{\arrowR};
\end{tikzpicture}
\begin{tikzpicture}
    %Triangle 3
    \node at (2,-1) {triangle 2};
    \draw (0,0)--(0,4) node[sloped,pos=0.5]{\arrowR};
    \draw (0,4)--(4,0) node[sloped,pos=0.5]{\arrowL};
    \draw (0,0)--(4,0) node[sloped,pos=0.5]{};
\end{tikzpicture}
\begin{tikzpicture}
    %arrows 1
    \node at (2,-1) {horizontal};
    \draw (0,0)--(4,0) node[sloped,pos=0.5]{\arrowL}; % makes an arrow pointing from the first coordinate to the last one to the left
    \draw (0,1)--(4,1) node[sloped,pos=0.5]{\arrowR}; % makes an arrow pointing from the first coordinate to the last one to the right.
    
\end{tikzpicture}
\begin{tikzpicture}
    %arrows 2
    \node at (2,-1) {vertical};
    \draw (1,0)--(1,4) node[sloped,pos=0.5]{\arrowL}; % makes an arrow pointing from the first coordinate to the last one down
    \draw (2,0)--(2,4) node[sloped,pos=0.5]{\arrowR}; % makes an arrow pointing from the first coordinate to the last one up
\end{tikzpicture}
\end{document}