In total internal reflection when the angle of incidence is equal to the critical angle for the pair of media in contact, what will be angle of refraction?

[Image showing light ray incident at critical angle and grazing the surface at 90 degrees]By definition, the critical angle ($i_c$) is the angle of incidence in the denser medium for which the angle of refraction in the rarer medium is exactly $90^{\circ }$. The refracted ray grazes the interface between the two media. If the angle of incidence exceeds $i_c$, total internal reflection occurs.