title: How to use the PI constant in Dart
body: <p>I imported <a href="https://api.dartlang.org/stable/2.0.0/dart-math/dart-math-library.html" rel="noreferrer">math</a>.</p>
  
  <pre><code>import 'dart:math';
  </code></pre>
  
  <p>But how can I call "PI" constant?</p>
  
  <p>This is not working.</p>
  
  <pre><code>   math.pi / 12.0
  </code></pre>