# How to indicate graphically that two sides are of equal length?

I'm using tikz to draw two triangles, e.g.

\begin{tikzpicture}[thick]
\coordinate (A) at (0,0);
\coordinate (B) at ($(A)+(330:3)$);
\coordinate (C) at ($(A)+(230:4)$);
\draw (A) node[above]{$A$} --(B) node[right]{$B$} -- (C) node[left]{$C$} --cycle;
\tkzMarkAngle[size=1.0](C,A,B)

\begin{scope}[rotate=75]
\coordinate (A) at (0,-5);
\coordinate (B) at ($(A)+(330:3)$);
\coordinate (C) at ($(A)+(230:4)$);
\draw (A) node[above]{$A$} --(B) node[right]{$B$} -- (C) node[left]{$C$} --cycle;
\tkzMarkAngle[size=1.0](C,A,B)
\end{scope}
\end{tikzpicture}


The two triangles are congruent and, as such, I'd like to use the normal notation to indicate that, i.e. a single tick on each of the lines AB on each triangle and a double tick on each of the lines AC.

I could add a length, e.g. x or y to each, but that's not an ideal solution.

I've tried adding in a midway point in the draw command to use a '-' or an '=', but that only really works if the line is horizontal or vertical otherwise I have to calculate the angle, which doesn't seem right.

Am I just missing out some simple instruction because I, maybe, just don't know the correct term for those marks?

• Welcome to TeX.SE. For future reference, it is always best to compose a fully compilable MWE that illustrates the problem including the \documentclass and the appropriate packages so that those trying to help don't have to recreate it. This is especially important for tikz as there are numerous libraries. – Peter Grill Jun 5 '14 at 19:25

\documentclass{article}

\usepackage{tikz,tkz-euclide}
\usepackage{siunitx}
\usepackage{pgfplots}
\usetikzlibrary{calc}
\usetkzobj{all}

\begin{document}
\begin{tikzpicture}[thick]
\coordinate (A) at (0,0);
\coordinate (B) at ($(A)+(330:3)$);
\coordinate (C) at ($(A)+(230:4)$);
\draw (A) node[above]{$A$} --(B) node[right]{$B$} -- (C) node[left]{$C$} --cycle;
\tkzMarkAngle[size=1.0](C,A,B)
\tkzMarkSegment[color=blue,pos=.5,mark=||](A,C)
\tkzMarkSegment[color=red,pos=.5,mark=s|](A,B)
\begin{scope}[rotate=75]
\coordinate (A) at (0,-5);
\coordinate (B) at ($(A)+(330:3)$);
\coordinate (C) at ($(A)+(230:4)$);
\draw (A) node[above]{$A$} --(B) node[right]{$B$} -- (C) node[left]{$C$} --cycle;
\tkzMarkAngle[size=1.0](C,A,B)
\tkzMarkSegment[color=blue,pos=.5,mark=||](A,C)
\tkzMarkSegment[color=red,pos=.5,mark=s|](A,B)
\end{scope}
\end{tikzpicture}
\end{document}


• Ah-hah - \tkzMarkSegment - that's the one! Thanks. – Unsliced Jun 5 '14 at 19:21
• Do you know if there's a way to get those marks perpendicular to their segments? The marks on AB in each figure look weird. Or is mark=s| causing that? – wchargin Jun 6 '14 at 2:20
• Use \tkzMarkSegment[color=red,pos=.5,mark=|](A,B) – ferahfeza Jun 6 '14 at 8:54