Adding to the previous post of math for graphics my main goal was creating a collision detection system.  Here are some references.

This was very helpful in giving a great explanation in collision detection and also had some nice diagrams which helped me understand the points.  Explained collision detection among  a variety of shapes.

http://www.metanetsoftware.com/technique/tutorialA.html

Basic physics 2D physics engine with some pseudo code:

http://www.wildbunny.co.uk/blog/2011/04/06/physics-engines-for-dummies/

More collision detection basics:

http://www.digitalrune.com/Support/Blog/tabid/719/EntryId/52/Continuous-Collision-Detection-ndash-Solutions.aspx

Theory of reflection through billiards explanation:

http://angleofreflection.wordpress.com/category/theory/