Brewster's angle is defined as the angle of incidence at which the reflection of particular polarized light is zero, and it perfectly transmitted through a transparent surface.
Brewster's angle(ib) is given by, tan(ib)=μ1μ2=1μ2, where μ2 is the refractive index of the dielectric and μ1 is the refractive index of air.
We know that, μ2>1. (refractive index of any dielectric will be greater than refractive index of air.)
⇒∞<tanib>1
⇒90o>ib>45o