The inverse of Cosxis a function. The domain of Cosxcould be ???

How would I find the domain???

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- Aug 2nd 2010, 03:31 PMMATNTRNGTrigonometric Function
The inverse of Cos

*x*is a function. The domain of Cos*x*could be ???

How would I find the domain??? - Aug 2nd 2010, 04:11 PMProve It
In order for $\displaystyle \textrm{Cos}\,{x}$ to have an inverse function, it must be one-to-one.

Draw the function $\displaystyle \cos{x}$. Can you choose a domain where there aren't any repeating $\displaystyle y$ values? - Aug 2nd 2010, 04:31 PMeumyang
Hmm... I'm assuming that the fact that C is capitalized is significant. I only learned $\displaystyle f(x) = \cos \,x$ when I was in school, and had never seen $\displaystyle f(x) = Cos \,x$ until now. Is it a regional/national thing? I'm in the US.

- Aug 2nd 2010, 04:34 PMProve It
The capitalisation means there has been a standard restriction on the domain of $\displaystyle \cos{x}$. It's up to you to find what that domain is.

Like I said, draw the function, and choose a domain in which there are not any repeating $\displaystyle y$ values. - Aug 2nd 2010, 04:39 PMMacstersUndead
Try looking at this interval. :)

$\displaystyle [0,\pi]$

edit:// mind blanked. - Aug 2nd 2010, 04:42 PMProve It