일반물리학 1 — Motion in Two and Three Dimensions: Problem 41

41 Upon spotting an insect on a twig overhanging water, an archer fish squirts water drops at the insect to knock it into the water (Fig. 4-29). Although the insect is located along a straight line path at angle $\phi$ and distance $d$, a drop must be launched at a different angle $\theta_0$ if its parabolic path is to intersect the insect. If $\phi = 36.0^\circ$ and $d = 0.900\text{ m}$, what launch angle $\theta_0$ is required for the drop to be at the top of the parabolic path when it reaches the insect?