11) Suppose that the right-hand face of your cube is recut so that it is at an angle relative to the other faces. By how many degrees would the right-hand face of your cube need to be angled (relative to as it is now) so that $\theta_g'$ would be large enough for your existing ray to totally internally reflect at that interface? This is the basis of gemstone cutting. Sketch a diagram of your recut former-cube, showing total internal reflection occurring at both the top and right faces.