If N=1.40, what is the largest angle of incidence for which total internal reflection will occur at the vertical face

A ray of light is incident in air on a block of a transparent solid Part A whose index of refraction is n. If n = 1.40, what is the largest angle of incidence 0. for which total internal reflection will occur at the vertical face (point A shown in the figure (Figure 1))? IVO AEQ 5 0 0 E ? O U = Submit Request Answer