Answer:
distance=5.74 m
Step-by-step explanation:
velocity components:

acceleration components

since the dolphin is moving horizontally going through the center of the hoop, we can assume that the vertical velocity=0
We can thus find the distance required to reach the hoop by kinematics:

(Roughly)
Or you can use the formula for maximum height of a body (in this case the dolphin) undergoing projectile motion:
