As shown in the figure, a ray AB of unpolarized light enters from water of refractive index nw = 4/3 into a medium of refractive index np = 4/√3 after passing through a glass plate of refractive index ng = 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: