How do I place braces on a line segment?

Question

So I have this code here,

   \begin{tikzpicture}

    % Draw the axes
    \draw [->,black] (-1.5,0) -- (3,0) ;
    \draw [->,black] (0,-1.5) -- (0,3) ;

    % Draw the line
    \draw[-,black](0,0)--(3,2);

    % Draw the circle
    \path [draw,green] (+1.5,0) circle (1.5);
    \path [draw,cyan] (0,1.5) circle (1.5);

    % Intersection of circle and line
    \draw[dashed,cyan](0,0.93)--(1.38,0.93);
    \draw[dashed,cyan](1.38,0.93)--(1.38,0);
    \draw[dashed,green](0,1.38)--(2.1,1.38);
    \draw[dashed,green](2.1,0)--(2.1,1.38);
  %  \node[] at (-0.25,1.78){$y$};

     \node[] at (-0.25,0.93){$y_3$};
     \node[] at (1.38,-0.25){$x_3$};


\coordinate (a) at (0,0);
      \coordinate (b) at (1.38,0.93);
    \draw[decorate,decoration={brace,amplitude=5pt,raise=1pt,mirror},yshift=0pt] (a) -- (b) node [midway,yshift=-10pt, xshift = 10pt]{$|z_3|$};
     \node[] at (-0.25,1.38){$y_2$};
     \node[] at (2.1,-0.25){$x_2$};  

   % \node[] at (2.9,-0.25) {$x$};

    % Draw the angle
    \draw [red] (0,0.3) arc (90:33:0.3);
    \draw[red] (0,0.4)arc(90:33:0.4);
    \node[] at (60:.6)  {$\alpha$};

    % Done
\end{tikzpicture}

, which gives me the following image:

enter image description here

However, what I would like to do is make brace/markers on the segments shown in the picture. (It is clear where I have hand-drawn them in).

How can I modify the above to be able to do so?

have a look at this answer: http://tex.stackexchange.com/questions/20885/draw-curly-braces-in-tikz — papabravo, May 15 '13 at 12:36
@ratatosk Please see my edit. I added the draw/decoration code, however I seen to have an issue with the size of the font. It is masking the brace... — Spacey, May 15 '13 at 12:53

Gonzalo Medina · Accepted Answer · 2013-05-15T17:47:44.487

For the braces, you can use the brace decoration. You can use the intersections library to calculate the intersection points between the line and the circles; in this way, you don't have to manually calculate coordinates; I also reduced the font size to \scriptsize:

\documentclass{article}
\usepackage{tikz}% just for the example
\usetikzlibrary{decorations.pathreplacing,intersections}
\begin{document}

 \begin{tikzpicture}[every node/.append style={font=\scriptsize}]

    % Draw the axes
    \draw [->,black] (-1.5,0) -- (3,0) ;
    \draw [->,black] (0,-1.5) -- (0,3) ;

    % Draw the line
    \path[name path=line,draw,-] (0,0) -- (3,2);

    % Draw the circle
    \path [name path=greencircle,draw,green] (+1.5,0) circle (1.5);
    \path [name path=bluecircle,draw,cyan] (0,1.5) circle (1.5);

% find intersections of line and circles
\path[name intersections={of=line and bluecircle, by={a,b}}];
\path[name intersections={of=line and greencircle, by={c,d}}];

% lines from axes to intersection points
    \draw[dashed,cyan] (0,0|-b) -- (b);
    \draw[dashed,cyan] (b|-0,0) -- (b);
    \draw[dashed,green] (0,0|-c) -- (c);
    \draw[dashed,green] (c|-0,0) -- (c);;
  %  \node[] at (-0.25,1.78){$y$};

     \node[left] at (0,0|-b) {$y_3$};
     \node[below] at (b|-0,0) {$x_3$};

     \node[left] at (0,0|-c) {$y_2$};
     \node[below] at (c|-0,0) {$x_2$};  

   \coordinate (O) at (0,0);
% draw braces
    \draw[decorate,decoration={brace,amplitude=5pt,raise=0.5pt,mirror},yshift=0pt] (O) -- (b) node [midway,yshift=-9pt, xshift =6pt]{$|z_3|$};
    \draw[decorate,decoration={brace,amplitude=5pt,raise=0.5pt},yshift=0pt] (O) -- (c) node [midway,yshift=11pt, xshift =-5pt]{$|z_2|$};

   % \node[] at (2.9,-0.25) {$x$};

    % Draw the angle
    \draw [red] (0,0.3) arc (90:33:0.3);
    \draw[red] (0,0.4)arc(90:33:0.4);
    \node[] at (60:.6)  {$\alpha$};

    % Done
\end{tikzpicture}
\end{document}

enter image description here

Thanks so much! Some questions: 1) How do I move the curvy part of the brace to somewhere arbitrary? (Right now it is in the middle. What if I want to make it like, 1/3 of the way?) 2) I know that I can use font=\tiny for the font of the text, however is there something smaller than tiny? Thanks a million! :) — Spacey, May 15 '13 at 13:23
@Mohammad 1) you can use the aspect key to give a fraction of the total length where the "middle part" of the brace will be, an example: decoration={brace,aspect=.33,amplitude=5pt,raise=0.5pt} 2) If your font allows it, you can use smaller sizes: \fontsize{3}{4}\selectfont — Gonzalo Medina, May 15 '13 at 13:31
If you want braces or brackets perpendicular instead of parallel to the line, is the best way to just place two nodes around a point on the line and connect a brace to each? — bright-star, Mar 08 '14 at 19:50
@TrevorAlexander that would depend on what you actually are trying to achieve. Please feel free to open a new question. — Gonzalo Medina, Mar 08 '14 at 23:04
I figured it out with help from this question. A simple way is just: \node (thisbracket) at (3,0) {]}; — bright-star, Mar 08 '14 at 23:08

How do I place braces on a line segment?

1 Answers1