Which formula represents Snell’s law?

Snell’s law relates the refractive indices of two media to the sines of the angles measured from the normal: n₁ sin θ₁ = n₂ sin θ₂. Therefore, choice A is correct. The cosine formulas and the formulas that add the refractive index to a trigonometric value are not Snell’s law.

AI-written and checked against the verified answer.