Hi, can you help me to solve this problem step by step, please?

Two microwave beams are incident normal to the surface of a large wedge of chocolate as shown in Figure 4. If the refractive index for chocolate relative to air for these microwaves is 1.2. Calculate the angle between the two emerging beams, shown as in the diagram.

Note: It can be assumed that the chocolate does not melt due to the microwave.