# Thread: Finding an Expression

1. ## Finding an Expression

I have no idea how to do this question..

cos^2(cos^(-1)(6/x))

Please see the attached for info

Thanks!

2. Originally Posted by gearshifter
I have no idea how to do this question..

cos^2(cos^(-1)(6/x))

Please see the attached for info

Thanks!
Read this thread for a way of doing questions like this: http://www.mathhelpforum.com/math-he...xpression.html

3. Originally Posted by gearshifter
I have no idea how to do this question..
That is the same as $\left(cos(cos^{-1}(6/x))\right)^2$. IMPORTANT: the "-1" on the cos mean "inverse function" not reciprocal! You should know that $f(f^{-1})(x)= x$.