title: Why dose cos(90) not equal zero?
body: <p>I understand that cos(); in c++ uses radians right.. and you can get radians with.. </p>
  
  <pre><code> (angle * PI ) / 180;
  </code></pre>
  
  <p>So why does</p>
  
  <pre><code> float value = cos( (90 * PI / 180 ); // == 6.1 etc... and not 0?
  </code></pre>
  
  <p>If I use the scientific calculator in windows for <code>cos(90)</code> I get zero.  Yet as an experiment, when I push <code>cosh(90)</code>, I get that same 6.1 etc... value that calling the function in C++ gave me.</p>
  
  <p>Any ideas what is going on?  Here is my code as it is now...</p>
  
  <p><a href="http://ideone.com/YQgLz" rel="nofollow">http://ideone.com/YQgLz</a></p>
  
  <p>What I am asking basically is why is <code>cos(90 degrees)</code> in C++ coming back with the same number as doing <code>cosh(90)</code> on the windows calculator.  Isn't <code>cos(90 degrees)</code> supposed to be zero anyway?</p>