How do you evaluate $tan^-1(tan((7pi)/10))$ ?

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Answer 1 · 2017-05-13T20:35:22

This is an example of any inverse function evaluated at the function always returns the argument:

$f^-1(f(x)) = x$

$:.$

$tan^-1(tan((7pi)/10))= (7pi)/10$

How do you evaluate tan^-1(tan((7pi)/10))tan^-1(tan((7pi)/10))?