A ray of light from a denser medium strike a rarer medium at an angle of incidence i (see Fig). The reflected and refracted rays make an angle of 90° with each other. The angles of reflection and refraction are r and r’. The critical angle is
(a) sin–1(tan r) (b) sin–1(tan i)
(c) sin–1(tan r) (d) tan–1(tan i)
