98. (a) The Sun is far enough away that we approximate its rays as “parallel” in this Figure. That is, if the sunray makes angle θfrom horizontal when the bird is in one position, then it makes the same angle when the bird is any other position. Therefore, its shadow on the ground moves as the bird moves: at 15 m/s. (b) If the bird is in a position, a distance x> 0 from the wall, such that its shadow is on the wall at a distance 0 ≥y≥hfrom the top of the wall, then it is clear from the Figure that tan= y/x. Thus,
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