A ray through a glass slab

A ray falls at $60^\circ$ on a glass slab $4\ \text{cm}$ thick, with $n = 1.5$. You will make the program find the angle inside the glass, the sideways shift of the ray, and the angle at which it leaves. Then it draws the path.

The idea. $\sin r = \dfrac{\sin i}{n}$, the shift is $d = \dfrac{t \sin(i - r)}{\cos r}$, and at the far face, $\sin e = n \sin r$.

Your tasks.

1. Work out r, the angle inside the glass, in degrees.
2. Work out d, the lateral displacement, in cm.
3. Work out e, the angle of emergence, in degrees.