Answer: 48 ft
Step-by-step explanation:
Given
Height of street light h=12 ft
length of shadow x=18 ft
Shadow length of building x'=72 ft
suppose the height of the building is y
from the figure, we can write
[tex]\Rightarrow \tan p=\dfrac{h}{x}=\dfrac{12}{18}\\\\\Rightarrow \tan p=\dfrac{y}{x'}=\dfrac{12}{18}\\\\\Rightarrow y=72\times \dfrac{2}{3}=48\ ft[/tex]