Trigonometry · NDA previous year questions

2013 3 questions

1. Q422013 · 14 Apr 2013

   In any triangle ABC, a = 18, b = 24 and c = 30. Then what is sin C equal to?

   1. A.1/4
   2. B.1/3
   3. C.1/2
   4. D.1
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   Answer: D

2. Q432013 · 14 Apr 2013

   If ${\sin }^{-1}\left(\frac{2a}{1+a^2}\right)+{\sin }^{-1}\left(\frac{2b}{1+b^2}\right)=2{\tan }^{-1}x$, then x is equal to

   1. A.$\frac{a-b}{1+ab}$
   2. B.$\frac{a-b}{1-ab}$
   3. C.$\frac{2ab}{a+b}$
   4. D.$\frac{a+b}{1-ab}$
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   Answer: D

3. Q442013 · 14 Apr 2013

   A man walks 10 m towards a lamp post and notices that the angle of elevation of the top of the post increases from $30^{\circ }$ to $45^{\circ }$. The height of the lamp post is

   1. A.10 m
   2. B.$(5\sqrt{3}+5)\text{ m}$
   3. C.$(5\sqrt{3}-5)\text{ m}$
   4. D.$(10\sqrt{3}+10)\text{ m}$
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   Answer: B