cfiandra” post=90073E credo che con qualche acrobazia si possa pure venire a capo del problema, se ho tempo vedo come fare.
Una possibile soluzione:
Spoiler
`
\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{center}
\begin{tikzpicture}[scale=1, line join=bevel]
% \a and \b are two macros defining characteristic
% dimensions of the Penrose triangle.
\pgfmathsetmacro{\a}{2.5}
\pgfmathsetmacro{\b}{0.9}
\tikzset{%
apply style/.code = {\tikzset{#1}},
triangle_edges/.style = {thick,draw=black}
}
\foreach \theta/\facestyle/\testo in {%
0/{triangle_edges, fill = gray!50}/{$a$},
120/{triangle_edges, fill = gray!25}/{$b$},
240/{triangle_edges, fill = gray!90}/{$c$}%
}{
\begin{scope}[rotate=\theta]
\draw[apply style/.expand once=\facestyle]
({-sqrt(3)/2*\a},{-0.5*\a}) —
++(-\b,0) —
({0.5*\b},{\a+3*sqrt(3)/2*\b}) — % higher point
({sqrt(3)/2*\a+2.5*\b},{-.5*\a-sqrt(3)/2*\b}) % rightmost point
node [pos=0.5, rotate=\theta+180*(\theta>150?1:0),
sloped, anchor=-90+180*(\theta>150?1:0)] {\testo} —
++({-.5*\b},-{sqrt(3)/2*\b}) — % lower point
({0.5*\b},{\a+sqrt(3)/2*\b}) —
cycle;
\end{scope}
}
\end{tikzpicture}
\end{center}
\end{document}`
Ciao