A ray of light is incident on a transparent glass slab of refractive index $1.62$ . If the reflected and refracted rays are mutually perpendiculars, what is angle of incidence?

Question

$(a)\;\tan^{-1} 1.31 \\ (b)\;\tan ^{-1} 1.5 \\ (c)\;\tan ^{-1} 1.62 \\ (d)\;\tan ^{-1} 2.5 $