title: Square root with javascript returns ReferenceError
body: <p>I'm trying to get the square root of a number using javascript.<br>
  To do that, I tried the following codes:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>&lt;script&gt;
  var rad = sqrt(4);
  alert(rad);
  &lt;/script&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>(this returns in Firefox's console "ReferenceError: sqrt is not defined")</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>&lt;script&gt;
  var rad = pow(4,0.5);
  alert(rad);
  &lt;/script&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>(but I get "ReferenceError: pow is not defined")</p>
  
  <p>What am I doing wrong?</p>