When the reflected light is completely polarized, the angle of incidence equals the Brewster angle.
According to Brewster’s law:
$$ \tan i_B = \frac{n_{glass}}{n_{air}} $$
$$ \tan i_B = 1.52 $$
$$ i_B = \tan^{-1}(1.52) = 57.7^\circ $$
At Brewster angle, the reflected and refracted rays are perpendicular to each other:
$$ i_B + r = 90^\circ $$
$$ r = 90^\circ - 57.7^\circ $$
$$ r = 32.3^\circ $$
Final Answer: $$ \boxed{32.3^\circ} $$