Answer:
Lamppost is 20.26 ft. tall.
Explanation:
In the figure attached. AB is the lamp post and DE is a man standing 10 ft away from the lamp post.
Therefore, in ΔABC,
term 50° =

term 50° =

1.192 =

AB = 17 × 1.192
= 20.26 ft.
Therefore, Lamppost is 20.26 ft. tall.