Question

The equilateral glass prism shown has an index of refraction of 1.56. The prism is surrounded by air. A ray of light is incident on the middle of the left face of the prism. What is the smallest angle of incidence for which the ray of light will emerge from the right face of the prism.

Incident ray hits the left side of the triangle going up and then refract down toward normanl inside the prism.