8. When a man stands near the edge of an empty drainage ditch of depth 2.80 m, he can barely see the boundary between the opposite wall and bottom of the ditch as in Figure a. The distance from his eyes to the ground is 1.85 m. The index of refraction of water is 1.33. (a) What is the horizontal distance d from the man to the edge of the drainage ditch? (b) After the drainage ditch is filled with water as in Figure b, what is the maximum distance x the man can stand from the edge and still see the same boundary