If
\[
y=\sin^{-1}\!\left(\frac{1-\cos2x}{1+\sin^{4}x}\right),
\]
then
\[
\frac{dy}{dx}=
\]
Show Hint
Remember the useful identity
\[
\boxed{
\sin\!\left(2\tan^{-1}t\right)
=
\frac{2t}{1+t^2}.
}
\]
Whenever an expression is of the form
\[
\frac{2t}{1+t^2},
\]
replace it by
\[
\sin\!\left(2\tan^{-1}t\right)
\]
to simplify inverse trigonometric differentiation.