1. The problem statement, all variables and given/known data We look at the center of one face of a solid cube of glass on a line of sight making 55° with the normal to the cube face. What is the minimum refractive index of glass for which you will see through the opposite face of the cube? (Hint: see through will be possible if the ray refracted on the first face can emerge from the opposite face) 2. Relevant equations Snells law: n1sin(x1) =n2sin(x2) Where n1 and n2 are the indices of refraction and x1 if the angle of incidence while x2 is the angle of refraction. Case of total internal reflection: N1sin(x1) = n2sin90 3. The attempt at a solution I tried finding the critical angle of incidence but I got no where.. been working on this for 12 hours, i feel like im seriously missing something! Help!