Question

A 150 cm tall boy stands at a distance of 8m from a lamp post and cast a shadow of 2m find the height of the lamp post

Answer 1

If the stands near the lamp post how is it possible to cast a shadow towards the lamp post .... Definitely the shadow is opposite to lamp post.

Answer 2

Thank you for asking this question.

Here is your answer:

Let AB be boy = 1.5m

CD be lamp = Let it be x m.

OB be shadow cast by boy = 4.5m

BD be distance between boy and lamp = 3m

Therefore

In ΔAOB,

= tan θ = AB/OB

In ΔCOD,

= tan θ = CD/OD = CD/(OB+BD)

∴ AB/OB = CD/(OB+BD)

=1.5/4.5 = CD/(4.5+3)

= CD = 7.5/3 = 2.5m

If there is any confusion please leave a comment below.