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NTA Abhyas 2020
Exam
NTA Abhyas
Year
2020
Subject
Mathematics
Chapter
Heights and Distances

NTA Abhyas 2020 · Mathematics · Heights and Distances

A pole is situated at the centre of a regular hexagonal park. The...

A pole is situated at the centre of a regular hexagonal park. The angle of elevation of the top of the vertical pole when observed from each vertex of the hexagon is π3.\dfrac{π}{3} . If the area of the circle circumscribing the hexagon is 27m227m^{2}, then the height of the tower isA pole is situated at the centre of a regular hexagonal park. The angle of elevation of the top of the vertical pole

Options

  1. A33πm3\sqrt{\dfrac{3}{\pi}}m
  2. B3πm\dfrac{3}{\sqrt{\pi}}m
  3. C3πm\sqrt{\dfrac{3}{\pi}}m
  4. D9πm\dfrac{9}{\sqrt{\pi}}m

Correct answer

D. 9πm\dfrac{9}{\sqrt{\pi}}m

Step-by-step solution

Let aa be the side of the regular hexagon

Now, for the equilateral triangle FOA,FOA, we have

OF=OA=AF=aOF = OA = AF = a

Hence, area of circle,~\pia2=27⇒a=33π\pia^{2} = 27 ⇒ a = 3\sqrt{\dfrac{3}{\pi}} meters ... \left(1\right)<br/><br/><imgsrc="/api/proxy−image?url=https<br /><br /><img src="/api/proxy-image?url=https%3A%2F%2Ffirebasestorage.googleapis.com%2Fv0%2Fb%2Fquantrexacademy-app.firebasestorage.app%2Fo%2Fquestions%252Ffigs%252Fnta_abhyas%252Fjee_main%252Fimages%252Faavfzumnxiatvzharkujlhndtwikoxlrqhehyrzwtqvfmkocuo.png%3Falt%3Dmedia&clean=1&v=wm2" data-qx-orig-src="https://firebasestorage.googleapis.com/v0/b/quantrexacademy-app.firebasestorage.app/o/questions%2Ffigs%2Fnta_abhyas%2Fjee_main%2Fimages%2Faavfzumnxiatvzharkujlhndtwikoxlrqhehyrzwtqvfmkocuo.png?alt=media" data-qx-storage-src="https://firebasestorage.googleapis.com/v0/b/quantrexacademy-app.firebasestorage.app/o/questions%2Ffigs%2Fnta_abhyas%2Fjee_main%2Fimages%2Faavfzumnxiatvzharkujlhndtwikoxlrqhehyrzwtqvfmkocuo.png?alt=media" /><br /><br />In right-angled triangleAOT,rightangledatright angled atO,wehave<br/><br/>we have<br /><br />\tan \left(\dfrac{\pi}{3}\right) = \dfrac{OT}{OA} ⇒ OT = OAtan\dfrac{\pi}{3} ⇒ OT = 3\sqrt{\dfrac{3}{\pi}} \times \sqrt{3}<br/><br/><br /><br />∴ OT = \dfrac{9}{\sqrt{\pi}}meters<br/><br/>meters<br /><br />∴ Heightofthetower~Height of the tower= \dfrac{9}{\sqrt{\pi}}$ meters.
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