If tan (π/2 -α/2)=√3, then the value of cos α is :

  1. 1/2
  2. 0
  3. √3/1
  4. 1/√2
Anurag Mishra Professor Asked on 29th December 2015 in Maths.
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  • 1 Answer(s)

    Answer is 1/2. 

    Explanation:-
    tan (π/2 – α/2) = √3
    As we know that π = 180º

    Then, tan (180º/2 – α/2) = √3
    tan (90º – α/2) = tan 60º
    Comparing on both side,
    90º – α/2 =  60º
    – α/2 = 60º – 90º
    – α/2 = – 30º
    α/2 = 30º
    α = 2 x 30º
    α = 60º

    Then, cos 60º = 1/2

    Hence, the correct answer is option  (1) 1/2.

     

    Monis Rasool Professor Answered on 29th December 2015.
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