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kamlallem vaiphei

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· 1 Months ago

admin please verify this solution...According to Kiran publication, the distance between the two consecutive kilometre stones is 2km and thus the answer given by them is option (b)

Question:
From an aeroplane just over a straight road, the angles of depression of two consecutive kilometer stones situated at opposite sides of the aeroplane were found to be 60° and 30° respectively. The height (in km) of the aeroplane from the road at that instant is:
Options:
A) \(\sqrt[]{3}\)
B) \(\cfrac{\sqrt[]{3}}{2}\)
C) \(\cfrac{\sqrt[]{3}}{3}\)
D) \(\cfrac{\sqrt[]{3}}{4}\)
Solution:
Ans: (d)


Let AD = x \(\Rightarrow\) BD = 1 – x

In \(\triangle\)ADC,

tan 60o  =\(\cfrac{h}{x}\Rightarrow x=\cfrac{h}{\sqrt{3}}\)     .........(i)

In \(\triangle\)BCD,

tan 30o = \(\cfrac{h}{1-x}\)              .........(ii)

Putting the value of x into equ. (ii),


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