A ray of light traveling from material A to B?

Question

A ray of light traveling in material A strikes the interface between materials A and B at an angle of incidence of 65.3 . The angle of refraction is 39 . Find the ratio nA/nB of the refractive indices of the two materials

Answer 1

Snell's law states: nA/nB = sin(thetaB)/sin(thetaA) (ref.)
The angles of incidence and refraction are the angles the rays make to a line normal to the interface.
nA/nB = sin(39 deg)/sin(65.3 deg)