I'm not sure if this can be answered without the picture but I can't get it posted.
The problem gives theta(incident) and theta(r). It's a basic refraction through a transparent plastic piece. It askes for the index of regraction of this material.
ni * sin(theta,i) = nr * sin(theta,r)
The Attempt at a Solution
I figured since the don't give any more information that the ni value = 1 because it's assumed to be air. So I tried nr = ni * sin(theta,i)/sin(theta,r)
but this is not right...