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Misc. 1 - Chapter 2 Class 12 Inverse Trigonometric Functions (Term 1)

Last updated at March 22, 2023 by

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Misc 1 Find the value of cos-1 (cos⁡〖13π/6〗 ) Let y = cos-1 (cos⁡〖13π/6〗 ) cos y = cos 13π/6 cos y = cos (390°) But, Range of cos−1 is [0, π] 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 (𝜋/6) ∴ y = 𝝅/𝟔 Which is in the range of cos-1 i.e. [0, π] Hence , cos −1 (cos 13π/6 " " ) = 𝝅/𝟔 (As cos (360 + θ) = cos θ)

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.