- Communitative: r s = s r
- Distributive: r (s + t) = r s + r t
- Associative: a (s t) = (a s) t
Cosine Rule: <script type="text/javascript" src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=default"> $ a^{2} = b^{2} + c^{2} - 2bc\cos \theta $ </script>