8

I would like to draw a circle divided into 3 parts with text inside, same in each of the three parts (in the middle), using tikzpicture environment. Something like:

Circle example

All the circle and its interior must be black, and the text of each part must be using \(...\).

MWE:

\documentclass{article}
\usepackage[spanish]{babel}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{pgfplots}
\pgfplotsset{compat=1.15}

\begin{document}

\begin{center}
    \begin{tikzpicture}
        \draw (0,0) circle (3);

    \end{tikzpicture}
\end{center}
\end{document}

MWE

Thank you!

4 Answers 4

7

The interception points of the lines with the circle can easily be calculated using trigonometric functions. Once these points are known, drawing is straight forward:

\documentclass{article}
\usepackage[spanish]{babel}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{pgfplots}
\pgfplotsset{compat=1.15}

\begin{document}

\begin{center}
    \begin{tikzpicture}
        \draw (0,0) circle (3);
                \draw (0,3) -- (0,0) -- (3*0.866,-3*0.5) (0,0) -- (-3*0.866,-3*0.5);
                \node at (0,-1.5) {$\{A,B\}$};
                \node at (1.5*0.866,1.5*0.5) {$\{A,B\}$};
                \node at (-1.5*0.866,1.5*0.5) {$\{A,B\}$};
    \end{tikzpicture}
\end{center}
\end{document}

enter image description here

2
  • Hmm... I forgot to mention that I would like to change the size of the circle. \draw (0,0) circle (3); is too big now I see, so \draw (0,0) circle (2); would be fine. Quacksorry!
    – manooooh
    Commented Jul 26, 2018 at 0:06
  • 1
    @manooooh Just replace all 3* by 2* and 1.5* by 1*. I deliberately did not include them in the calculation of the lengths to be able to change them easily. Commented Jul 26, 2018 at 0:08
15

an alternative:

  • used polar coordinates
  • define radius of circle and with it also calculated distances of nodes from circle centre

    \documentclass[tikz, margin=3mm]{standalone}
    \usepackage[spanish]{babel}
    \usepackage[T1]{fontenc}
    \usetikzlibrary{babel}
    
    \begin{document}
        \begin{tikzpicture}
    \def\R{3cm} % defined radius of circle
    \draw (0,0) circle[radius=\R];
    \draw (0,0) -- (90:\R)    (0,0) -- (210:\R)     (0,0) -- (330:\R);
    %
    \node at ( 30:\R/2) {\(\{A,B\}\)};
    \node at (150:\R/2) {\(\{A,B\}\)};
    \node at (270:\R/2) {\(\{A,B\}\)};
        \end{tikzpicture}
    \end{document}
    

enter image description here

2
  • +1 for using polar coordinates. Students usually don't like to learn it.
    – Sigur
    Commented Jul 26, 2018 at 1:44
  • @Sigur, thank you very much! my experiences with students are similar ...
    – Zarko
    Commented Jul 26, 2018 at 6:00
6

I copied some Zako's code. I use tkz-euclide. The points B and C are found with rotation.

\documentclass[border=1.5mm,12pt]{standalone}
\usepackage{fouriernc}
\usepackage{tkz-euclide,amsmath} 
\usetkzobj{all} 
\tikzset{line/.style = {thick}}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
\def\R{2}
\tkzDefPoint(0,0){O}\tkzDefPoint(90:\R){A}
\tkzDefPointsBy[rotation=center O angle 360/3](A,B){B,C}
\tkzDrawCircle[R](O,\R cm)
\tkzDrawSegments[line](O,A O,B O,C)
\node at ( 30:\R/2) {\(\{A,B\}\)};
\node at (150:\R/2) {\(\{A,B\}\)};
\node at (270:\R/2) {\(\{A,B\}\)};
\end{tikzpicture}
\end{document}

enter image description here

5

Nobody proposed a circular node with its angular anchors.

\documentclass[tikz,border=2mm]{standalone} 

\begin{document}
\begin{tikzpicture}
\node[circle,draw, minimum width=4cm, outer sep=0pt] (a) {};
\foreach \i in {90,210,330}
    \draw (a.center)--(a.\i);

\foreach \i/\j in {30/{A,B},150/{E,F},270/{C,D}}
    \path (a.center) -- node {$\{\j\}$} (a.\i); 
\end{tikzpicture}
\end{document}

enter image description here

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