title: In Xcode, how can I import or use the normal BSD Unix C Library?
body: <p>The Stanford iOS dev seminar suggests I uses "the normal BSD Unix C" library for calculating sine and cosine. While I can calculate those values on my own just fine, I'm trying to learn more about implementing external libraries. </p>
  
  <p>Where is this library? Is it included by default?</p>
  
  <p>Cheers!</p>