# A 1.5m tall boy stands at a distance of 3m from a lamp post and casts a shadow of 4.5m on the ground.find the height of lamp post by trignometric ratios

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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 =