Wave Optics

As shown in the figure, a ray AB of unpolarized light enters from water of refractive index $n_w = \frac{4}{3}$ into a medium of refractive index $n_p = \frac{4}{\sqrt{3}}$ after passing through a glass plate of refractive index $n_g = 1.5$ and a layer of water. At a particular incident angle $i$ the reflected ray CD is polarized in the direction as shown in the figure. The value of $i$ (in degrees) is :