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RD Sharma Solutions Class 10 Mathematics Solutions for Some Applications Of Trigonometry Exercise 12.1 in Chapter 12 - Some Applications Of Trigonometry

Question 23 Some Applications Of Trigonometry Exercise 12.1

A 1.6 m tall girl stands at a distance of 3.2 m from a lamp post and casts a shadow of 4.8 m on the ground.

Find the height of the lamp post by using trigonometric ratio.

Answer:

Solution:

A common notion in trigonometry, specifically, is the angle of elevation, which has to do with height and distance. It is described as an angle formed by the horizontal plane and an oblique line between the observer's eye and a target above it.

R D Sharma Solutions - Mathematics - Class 10 chapter Some Applications Of Trigonometry Question 23 Solution image

Let AC be the lamp post of height ‘h’

DE is the tall girl and her shadow is BE.

So, we have ED = 1.6 m, BE = 4.8 m and EC = 3.2

By using trigonometric ratio

In ΔBDE,

tan θ = 1.6/4.8

tan θ = 1/3

Next, In ΔABC

tan θ = h/ (4.8 + 3.2)

1/3 = h/8

h = 8/3 m

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