In the figure, light enters a 90 degree triangular prism at point P with incident angle theta, and then some of it refracts at point Q with an angle of refraction of 90 degrees. (a) What is the index of refraction of the prism in terms of theta? (b) What, numerically, is the maximum value that the index of refraction can have? Does light emerge at Q if the incident angle at P is (c) increased slightly and (d) decreased slightly?