How do you evaluate ${cos}^{- 1} (cos (\frac{- 2 π}{3}))$ $cos^-1(cos((-2pi)/3))$ ?

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Answer 1 · 2016-02-11T17:23:22

Value of $cos^(−1)(cos(−2π/3))$ is $−2π/3$ .

The value of function $cos^(−1) x$ is equal to the value of the angle whose cosine is $x$ .

Assume $x=cos (−2π/3)$ .

Finding the value of $cos^(−1)(cos(−2π/3))$ means finding the value of $cos^(−1)x$

But if $x=cos (−2π/3)$ , obviously $cos^(−1)x=(−2π/3)$

Hence value of $cos^(−1)(cos(−2π/3))$ is $−2π/3$ .

How do you evaluate cos^-1(cos((-2pi)/3))cos−1(cos(−2π3))cos^-1(cos((-2pi)/3))?