Open Education Resources
The following Open Education Resources (OER) have been adapted to create this unit:
![here](http://By <a href="//commons.wikimedia.org/wiki/File:PolygonsSet.svg" title="File:PolygonsSet.svg">PolygonsSet.svg</a>: <a href="//commons.wikimedia.org/wiki/User:Kismalac" title="User:Kismalac">kismalac</a> / derivative work: <a rel="nofollow" class="external text" href="http://kulla.me/">Stephan Kulla</a> (<a href="//commons.wikimedia.org/wiki/User:Stephan_Kulla" title="User:Stephan Kulla">Stephan Kulla</a>) - <a href="//commons.wikimedia.org/wiki/File:PolygonsSet.svg" title="File:PolygonsSet.svg">PolygonsSet.svg</a>, <a href="http://creativecommons.org/publicdomain/zero/1.0/deed.en" title="Creative Commons Zero, Public Domain Dedication">CC0</a>, <a href="https://commons.wikimedia.org/w/index.php?curid=39323364">Link</a>){kind=link}