Answer:
y = 138.96 m
Step-by-step explanation:
The angle subtended by the moon is the mean of the angle of the arc between the two most extreme points of the moon, we can see that the angle is very small, so we can approximate this arc to a straight line and then use the trigonometric relationships
sin θ = y / L
where L = 15.9 10³ m and θ = 8.74 10⁻³ rad
y = L sin θ
y = 15.9 10³ sin (8.74 10⁻³)
y = 15.9 10³ 0.0087399
y = 138.96 m