Brewster angle and Fresnel reflection

What you are seeing: a light ray incident on an interface between two media at angle $\theta_i$. Snell s law $n_1 \sin\theta_i = n_2 \sin\theta_t$ gives the refraction angle; Fresnel coefficients give $R_s(\theta_i)$ and $R_p(\theta_i)$. At Brewster angle $\theta_B = \arctan(n_2/n_1)$ the p-reflectance vanishes; at the critical angle $\theta_c = \arcsin(n_2/n_1)$ (when $n_1 > n_2$) TIR sets in