Light is incident normally on the short face of a 30$^\circ$$-$60$^\circ$$-$90$^\circ$ prism ($\textbf{Fig. P33.50}$). A drop of liquid is placed on the hypotenuse of the prism. If the index of refraction of the prism is 1.56, find the maximum index that the liquid may have for the light to be totally reflected.