Hello mathlovers!
I have a sticky problem where I am unable to see how to simplify Sin(2u) where u=tan^-1 x
I get Sin(2tan^-1 x). How do you rewrite in a simpler math-language as wolfram does?
Not sure I follow how they compute this operation. Could someone fill me in?
Love
Anhard

Well Done and short Solution for the problem.
Your picture is blurred, so I cannot see what you are trying to accomplish. I hope the following helps:
u=tan-1 x implies tan(u)=x
By Pythagorean theorem:
sin(u)=x/sqrt(x^2+1)
cos(u)=1/sqrt(x^2+1)
sin(2u) = 2sin(u)*cos(u)
sin(2u) = 2x/(x^2+1)