What is the relationship between angle and polarization in modern optics?

[Duboo]

Homework Statement

Problem 2.18 is what I want to know. I think I have to use equation (eq 2.72) about phase difference in TIR, but , I'm not sure because n=1.65 so it's complicate..

Relevant Equations

At picture

 

[mfb]

Which part is unclear?
From geometry you can relate the angle at A to the angle for the reflection. From the condition that linearly polarized light becomes circular polarized light you can calculate the phase difference $\Delta$ you need. You don't need to solve for the angle here luckily, you just need to show that the given value makes the equation correct.