I need an explanation plzzz help :)

Answer:
117.6 ft
Step-by-step explanation:
You have two legs of the triangle and an angle, so you'll use tangent here. Sin and cos both involve hypotenuse, which you're not given.
Remember SOHCAHTOA
Tangent = Opposite / Adjacent
The side opposite the angle is the height, the side adjacent to the angle is the 25 ft.
tan(78°) = height / 25
25tan(78°) = height = 117.6 ft.