Also, there is a question as to how to find the critical angle of a "special glass" (the index of refraction of which I am not given... o.O) when submerged in water. Hereis the question:
"The critical angle for a special glass in air is 43°. What is the critical angle if the glass is immersed in water?"
I tried to use sin_theta=1/n, but I couldn't figure out how to set up the problem. Someone have an idea?