There's that attitude again. Don't get people to help you only to then use harsh language and curse words later
The graph of y=f(x) i.e. y=tan(x/2) is simply one branch of the tan curve with period 2pi.
On this domain, since f(x) is one-to-one it is indeed invertible. To find the inverse:
Consider x=tan(y/2)
Then arctan(x)=y/2 so y=2 arctan(x)
where arctan is just inverse tan if you have not seen it before. I.e. tan
-1(x)
So we have f
-1(x) = 2arctan(x)
This is a dilated version of the regular inverse tangent curve: the asymptotes are now at pi and -pi, instead of pi/2 and -pi/2
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