title: Enter a line break in node text in Latex Tikz library
body: <p>I've just started using Latex to produce a maths-heavy document. I wanted to include a probability tree and found the Tikz library. The first bit of the code for my tree looks like:</p>
  
  <pre><code>%To create probability trees, use tikz package
  \usepackage{tikz}
  \usetikzlibrary{trees}
  
  % Insert a probability tree showing first level only
  % -------------------------------------------------------------
  % Set the overall layout of the tree
  \tikzstyle{level 1}=[level distance=3.5cm, sibling distance=4.0cm]
  \tikzstyle{level 2}=[level distance=3.5cm, sibling distance=2cm]
  
  % Define styles for bags and leafs
  \tikzstyle{bag} = [text centered]
  
  % Draw probability tree
  \begin{tikzpicture}[grow=right, sloped]
  \node[bag] {}
      child {
          node[bag] {Not diseased $\left( D^- \right)$}
              edge from parent 
              node[below]  {$0.90$}
      }
      child {
          node[bag] {Diseased $\left( D^+ \right)$}        
              edge from parent         
              node[above] {Prevalence}
              node[below]  {$0.10$}
      };
  \end{tikzpicture} \\
  </code></pre>
  
  <p>The resulting tree looks a bit like this:</p>
  
  <pre><code>             Diseased (D+)
             /
      Prev /
         / 0.10
       /
       \
         \
     0.90  \
             \
               Not diseased (D-)
  </code></pre>
  
  <p>... if you get my drift.</p>
  
  <p>I would like to be able to enter a line break in the node text so that the (D+) and (D-) appear underneath. I've tried using \\ and \newline but to no avail. Any suggestions?</p>
  
  <p>Thanks in advance.</p>