Answer:
4.87 ft
Explanation:
The height of the skylight =
The height of the blue △ - the height of the red △
Let b ft be the height of the blue △.
sin 60° =

b = 25 sin 60°
Let r ft be the height of the red △.
tan 40° =

r = 20 tan 40°
The height of the skylight
= 25 sin 60° - 20 tan 40°
= 4.87 ft (rounded to the nearest hundredth)