1. The problem statement, all variables and given/known data I am studying the Law of Refraction. I am at a point in my textbook called a "checkpoint". These are supposed to be simple questions to test understanding. I'm apparently not understanding thus far because I cannot figure out this problem. http://img262.imageshack.us/img262/7029/refractionqn3.jpg [Broken] 2. Relevant equations Snell's Law? 3. The attempt at a solution I'm sure the angles of line segments b and c (relative to a?) will be the determining factor. Since the problem says "original materials a" does that mean we measure all angles relative to line segment a? How do I proceed more mathematically on this problem - perhaps using Snell's law?