# How do I mark an angle with multiple arcs?

I have been trying to find a good answer to this question (or a question to match it): I'm trying to give an angle a marking with multiple arcs in the interior, as per the pictures below. I'm not concerned with fill color, or anything else like that: is there a relatively simple way to mark an angle with more than one arc? So far, I haven't found anything in the decorations library, and the arc and style parameters on \tkzMarkAngle don't seem to work (at least, not very reliably). Am I missing anthing?

An ad hoc possibility is to use the angles library and then double for the double line and just to add a single arc for triple lines.

\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{angles}
\begin{document}
\begin{tikzpicture}[double arc/.style={double,double distance=2pt},
triple arc/.style={double distance=4pt,
pic actions/.append code=\tikzset{postaction={draw}}}]
\draw
(2,0) coordinate (A) -- (0,0) coordinate (B)
-- (1,1) coordinate (C)
pic [draw,double arc,angle radius=1cm] {angle=A--B--C};
\begin{scope}[xshift=4cm]
\draw
(2,0) coordinate (A) -- (0,0) coordinate (B)
-- (1,1) coordinate (C)
pic [draw,triple arc,angle radius=1cm] {angle=A--B--C};
\end{scope}
\end{tikzpicture}
\end{document}


• Yes angle pic use pic actions that do not include preaction and postaction. And this is normal because there are two paths, one filled and the other drawn, so to which one the preaction should be applied ? – Kpym Nov 2 '18 at 15:09
• @Kpym Yes. angles also adds a .center to the middle coordinates. One may improve it in a few ways. – marmot Nov 2 '18 at 15:20

It is possible to use the macro \tkzMarkAngle of the tkz-euclide package. It is not documented in the manual which is written in French but by looking at the sources .../tex/latex/tkz-euclide we find this:

% \tkzMarkAngle(B, A, C)
%
% Angle mark
% arc of circle (single/double/triple) and equality mark.
%
% By default:
% arc = simple
% length = 1cm (arc radius)
% style solid lines
% position: 0.5 (mark position)
% mark nothing at all (ignored if type is used)
%
% Parameters (optional)
% arc: l, ll, lll
% length: 1cm
% gap : 2pt
% style: type of lines
% type : none, |, ||, |||, z, s, x, o, oo
% position: 0.5
% mark : none, |, ||, |||, z, s, x, o, oo but all
% % % tikz symbols are allowed


I must say that I did not fully understand the use of all the parameters. Here is an example of a code:

\documentclass{article}
\usepackage{tkz-euclide}
\usetkzobj{all}
\begin{document}

\begin{tikzpicture}[scale=2]
\tkzDefPoint(0,0){O}
\tkzDefPoint(2,-1){A}
\tkzDefPoint(2,2){B}
\tkzDefPointsBy[symmetry=center O](B,A){}
\tkzDrawLine(A,A')
\tkzDrawLine(B,B')
\tkzDrawPoints(O,A,B,A',B')
\tkzLabelPoints[below](O)
\tkzLabelPoints(B,B')
\tkzLabelPoints[below left](A,A')
\tkzMarkAngle[mark=s,arc=l,type=||,size=2 cm,mkcolor=red](A,O,B)
\tkzMarkAngle[mark=||,arc=ll,size=1.5 cm,mkcolor=red](B,O,A')
\tkzMarkAngle[mark=s,arc=l,type=||,size=2 cm,mkcolor=red](A',O,B')
\tkzMarkAngle[mark=||,arc=ll,size=1.5 cm,mkcolor=red](B',O,A)
\end{tikzpicture}
\end{document}


And the result: