The horizontal distance between two poles is 15 m. The angle of depression of the top of the first pole as seen from the top of the second pole is 30°. If the height of the second pole is 24m, find the height of the first pole. 
In the fig let DC is the first pole
of height h (m)
In ∆AED
tan 30° = 
= 
√3h = 15
h = 
⇒ 8.66m
Therefore the height of first
pole is 24 – 8.66 = 15.34m
39