If a 1.5 m tall girl stands at a distance of 3 m from a lamp-post and casts a shadow of length 4.5 m on the ground, then the height of the lamp-post is
Let AB be the tower of h meters and CD be the girl of 1.6m height casting shadow = DE of 4.8 m, standing at the distance of 3.2m from the tower.
In Δ CDE
tan ∠CED = CD/ DE = 
………………….1
tan ∠CED = 1/3
In Δ ABE
tan ∠CED = 
= 
………………….2
From 1 and 2
= 
h = 
m
h = 2.5m
20