I added a screenshot with the complete question along with its diagram.
Answer:vertical height is approximately 260 ft
Explanation:We can note that the sea level, vertical height and the distance traveled by the rocket all form a right angled triangle.
This means that the special trig functions can be applied.
These functions are as follows:
sin θ = opposite / hypotenuse
cos θ = adjacent / hypotenuse
tan θ = opposite / adjacent
From the given we have:
θ = 60°
opposite is the vertical height that we want to find
hypotenuse = 300 ft
Applying the sin function, we can get the vertical height as follows:
sin (60) = opposite / 300
opposite = 300 * sin (60)
opposite = 259.807 which is approximately 260 ft
Hope this helps :)