How do you evaluate ${cos}^{- 1} (cos (\frac{3 π}{10}))$ $cos^-1(cos((3pi)/10))$ ?

Question

2638 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-11-16T18:06:29

${cos}^{- 1} (cos (\frac{3 π}{10})) = \frac{3 π}{10}$ $cos^-1(cos((3pi)/10)) = (3pi)/10$

Use a fundamental property of inverses: $f^{- 1} (f (x)) = x$ $f^-1(f(x)) = x$ .

How do you evaluate cos−1(cos(3π10))cos^-1(cos((3pi)/10))?