Q20 of 107 Page 12

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

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