If ∫sin2xcos4x+sin4xdx=tan−1(f(x))+C then
f(x)=x2
f(x)=cosx
f(x)=sinx
f(x)=tan2x
sin2xcos4x+sin4x=2sinxcosxcos4x+sin4x=2tanxsec2x1+tan4x
Now put tan2x=t.