Question

simplify cos(2*tan^-1(x))

Answer 1

\[\cos(2\theta)=2\cos^2(\theta)-1\] so
\[\cos(2\tan^{-1}(x))=2\cos^2(\tan^{-1}(x))-1\] is a good place to start

Answer 2

all you need now is an expression for
\[\cos(\tan^{-1}(x))\]

Answer 3

thank you! I t think I know how to solve it now!

Answer 4

yw