A 1.6m tall, girl stands ata distance of 3.2m from a lamp-post and cats a shadow of 4.8m on the grond. Find the height of the lamp-post by using (i)trignometric ratios (ii)property of similiar triangles.

Dear Student!

Let AB be the tower of height h m.

Suppose CD be the height of the girl and DE be the length of shadow of the girl.

Given, CD = 1.6 m, AD = 3.2 cm and DE = 4.8 m.

In ΔCDE,

In ΔBAE,

Thus, the length of the lamp post is

Method 2:

In ΔCDE and ΔBAE,

∠CED = ∠BEA  (Common)

∠CDE = ∠BAE  (90º)

∴ ΔCDE ∼ ΔBAE  (AA similarity criterion)

Thus, the length of the lamp post is

Cheers!

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