# Monochromatic Light and a 30-60-90 Prism Problem

## Homework Statement

Red light is incident in air on a 30o - 60o - 90 o prism as shown. The incident beam is directed at an angle of φ1 = 34.3o with respect to the horizontal and enters the prism at a height h = 26 cm above the base. The beam leaves the prism to the air at a distance d = 77.2 along the base as shown.

http://imgur.com/O9jZg

Snell's Law

## The Attempt at a Solution

So basically, I am getting really hung up with the geometry. I just can't figure out how to find angle 2. I've tried a couple of different triangles, and every useful one I come up with I can't solve and everyone I can solve, doesn't give me anything useful. My teacher said: "My suggestion is to focus on finding the second angle using geometry. My hint is to focus on h, which represents the distance from the point where the beam enters the prism to the bottom of the prism." I have literally been working on this for the past 2 days and I can't see what triangle to use.