There is just one angle of incidence β onto a prism for which the light inside an isosce...

There is just one angle of incidence β onto a prism for which the light inside an isosceles prism travels parallel to the base and emerges at that same angle β, as shown in Figure P18.57.

a. Find an expression for β in terms of the prism’s apex angle a and index of refraction n.

b. A laboratory measurement finds that β = 52.2° for a prism that is shaped as an equilateral triangle. What is the prism’s index of refraction?