Q11 of 120 Page 93

The angle of elevation of the top of a tower is 300. If the height of the tower is doubled, then the angle of elevation of its top will also be doubled.

False

Let height of tower is h and BC = x m.



In ∆ABC, tan 30°= AC/BC = h/x


…eq. 1


Now let height be 2h (doubled)



In



⇒ θ = tan-1(1.15) < 60°


(∵ tan-1 (1.15) = 49°)


Hence, the angle of elevation is not doubled when height is doubled.


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