Homework Help: Optics question - coin at the bottom of a swimming pool

1. Feb 27, 2013

Genericcoder

Optics question -- coin at the bottom of a swimming pool

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

The apparent depth of a pool depends on the angle of viewing. Suppose that you place a coin at the bottom of a swimming pool filled with water (n = 1.33) to a depth of 2.16m.
Find the apparent depth of the coin below the surface when viewed. a) at near normal incidence nd b)By rays that leave the coin making an angle of 35.0 with the normal to the bottom of the pool.

I solved part a but for part b what I don't understand is don't we need to know theta2 aswell
like here we know that

dapp = tan(theta1) / tan(theta2) * d;

where d is 2.16 and theta 1 = 35.0 don't we need to know theta2 to solve this ?

2. Feb 27, 2013

haruspex

Re: Optics question -- coin at the bottom of a swimming pool

Can't you use Snell's law to calculate theta2?