Snells law of refraction measuring displacement through medium

[georg gill]

Homework Statement

I have tried to solve the displacement sideways of an lightray through a medium with snells law. The question is how much does the ray travel in x-direction in the new medium with width D. It says in the text that one should use pytagoras but I can't seem to understand where the index n fits in the problemsolving. Belove is the answer. What does n mean for the trigonometrics? I have a link to the answer below. It almost looks like n is the hypotenuse but I can't see why if it is. The studyproblem is 3A

Homework Equations

https://acrobat.com/app.html#d=8LzuwGT8D*9EfoI9imptxg

The Attempt at a Solution

 

[georg gill]

I am sorry that the answer is in norwegian. It is the assignemnt oppgave 3. From the drawing they use snells law

n1sinx1=n2sinx2 og tan on the triangle with one angle at 90 degrees