Question

cos^-1(cos 7π/6) ans this​

Answer 1

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Answer 2

Answer:

let

y=cos^-1(cos 7π/6)

cos y =cos 7π/6

cos y =cos 210°

range of principal value of cos is (0,π) i.e. (0°,180°)

hence y≠210°

now

cos y =cos 210°

cos y=cos (360-150)°

{cos (360-theta)=cos theta}

cos y=cos 150°

y=150°= 5π/6

cos^-1(cos 7π/6)=150°=5π/6