For equal permeabilities (e.g., non-magnetic media), if θ i and θ t are complementary, we can substitute ‍ sin θ t ‍ for ‍ cos θ i ‍, and ‍ sin θ i ‍ for ‍ cos θ t ‍, so that the numerator in equation (31) becomes ‍ n 2 ‍ sin θ t − n 1 ‍ sin θ i ‍, which is zero (by Snell's law). Hence r p = 0 and only the s-polarized component is reflected. This is what happens at the Brewster angle. Substituting ‍ cos θ i ‍ for ‍ sin θ t ‍ in Snell's law, we readily obtain