Question

without this 2 more to finish
∫sin3x dx/1+cos3x
let,1+cos3x=z
or,d/dx(1)+d/dx(cos3x)=dz/dx
or,0-sin3x.3=dz/dx
or,sin3x dx=-dz/3

Now ∫sin3x dx/1+cos3x=∫-dz/3/z=-∫dz/3.1/z=-1/3∫1/z.dz=-1/3 lnz+c=-1/3 ln(1+cos3x)+c
is this correct?

Answer 1

its correct!
you're good at integrating :)

Answer 2

Thank you :)

Answer 3

you're most welcome ^_^

Answer 4

^_^