n₂ = index of refraction of glass = 1.58
n₁ = index of refraction of air = 1
θ = Brewster's angle
Brewster's angle is that incident angle at which the the reflected light from the interface of two medium is completely polarized.
Brewster's angle is given as
θ = tan⁻¹(n₂ /n₁ )
θ = tan⁻¹(1.58/1 )
θ = 57.7 deg
hence the Brewster's angle comes out to be 57.7 deg