Misc 1 - Find cos-1 (cos 13pi/6) - Chapter 2 Class 12 NCERT - Miscellaneous

  1. Chapter 2 Class 12 Inverse Trigonometric Functions
  2. Serial order wise
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Misc 1 Find the value of cos-1 (cos 13 /6 ) Let y = cos-1(cos 13 /6) cos y = cos 13 /6 cos y = cos (390 ) We know that range of principal value of cos is [0, ] i.e. [0 ,180 ] Hence y = 390 not possible Now, cos y = cos (390 ) cos y = cos (360 + 30 ) cos y = cos (30 ) cos y = cos (30 /180) cos y = cos ( /6) y = /6 Which is in the range of principal value of cos-1 i.e. [0, ] Hence , cos 1 (cos 13 /6 " " ) = y = /6

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.