title: Sin and Cos give unexpected results for well-known angles
body: <p>I am sure this is a really stupid question, but when I pass an angle of 180 degrees into c/c++'s cos() and sin() functions I appear to receive an incorrect value.  I know that it should be:
  sin of 0.0547 and cos of 0.99 
  but I get sin of 3.5897934739308216e-009 and cos of -1.00000</p>
  
  <p>My code is:</p>
  
  <pre><code>double radians = DegreesToRadians( angle );
  double cosValue = cos( radians );
  double sinValue = sin( radians );
  </code></pre>
  
  <p>DegreesToRadians() is:</p>
  
  <pre><code>double DegreesToRadians( double degrees )
  { 
      return degrees * PI / 180; 
  } 
  </code></pre>
  
  <p>Thank you :)</p>