[20 pts] An archer shoots an arrow horizontally at a target 15 m away. The arrow is aimed directly at the center of the target, but it hits 41.7 cm lower. [Answer in 3 significant figures] a) (12 pts) What is the initial speed of the arrow? b) (8 pts) In order to hit at the center of the target with the same initial speed, at what angle (low angle) should the archer shoot the arrow