5. (20%) A small bug is found in the "Jurassic Park" ruin embedded at the middle...
5. (20%) A small bug is found in the "Jurassic Park" ruin embedded at the middle of a rectangular block of amber (Er-155). The top surface of the amber block is a square of 5 cm by 5 cm and the height is 2 cm. Is it possible to cover a portion of the top surface of the block so that the bug will not be seen at any viewing angle from the top? If so, find the shape and the minimum area of the cover. Hint: Consider conditions of the total internal reflection, and neglect multiple internal reflections.