title: Error making app compatible for iOS6 and iOS7
body: <p>I built an app on XCode 5 for iOS7 and have just downloaded the iOS6 SDK so I can make the app compatible for iOS6, however when trying to build the project I am getting this error</p>
  
  <pre><code>Undefined symbols for architecture armv7:
    "___sincos_stret",
  </code></pre>
  
  <p>What should I do to solve this because I really need my app working with iOS6</p>
  
  <p>Here are my current settings:</p>
  
  <p><img src="https://i.stack.imgur.com/ylylj.png" alt="enter image description here"></p>
  
  <p><img src="https://i.stack.imgur.com/epmQ5.png" alt="enter image description here"></p>