In this question, I’m supposed to use sin instead of tan. But the question is worded weirdly. How can I know that I’m suppose to use sin?

Answer:
Since the kite is flying, the hypotenuse side of the triangle is 32.4m, while the adjacent side is unknown.
Given the opposite and hypotenuse, we use sine to find the angle.
[tex]\boxed{sinθ = \frac{opp}{hyp} }[/tex]
[tex]sinθ = \frac{18.3}{32.4} [/tex]
[tex]θ = {sin}^{ - 1} ( \frac{18.3}{32.4} )[/tex]
θ= 34.4° (1 d.p.)
Thus, the angle the kite string makes with the ground is 34.4°.
Notes:
[tex]cosθ = \frac{adj}{hyp} [/tex]
[tex]tanθ = \frac{ opp}{adj} [/tex]