Simplification of hyperbolic function

I'm having trouble seeing how this piece of manipulation follows:

I can see that a factor of a 1/2 has been taken out but otherwise I'm unsure how to deal with the sinh(2arcsinh(wr))

http://i1104.photobucket.com/albums/...ingproblem.jpg

Any help would be appreciated!

It's because . In this case, .


BTW, are you sure that it's and not ?

I hadn't even noticed it said sin. I'm pretty much certain that's a typo and as you say, it's supposed to be arcsinh.

Thanks!