How do you find the antiderivative of sinx/(1-cosx)sinx1cosx?

1 Answer
Jul 5, 2016

You can simply do a u-substitution.

Let:

u = -cosxu=cosx
du = sinxdxdu=sinxdx

Therefore, the antiderivative/integral is:

color(blue)(int sinx/(1-cosx)dx)sinx1cosxdx

= int 1/(1+u)du=11+udu

= ln|1+u|=ln|1+u|

= color(blue)(ln|1-cosx| + C)=ln|1cosx|+C

We know this works because:

color(green)(d/(dx)[ln|1-cosx| + C])ddx[ln|1cosx|+C]

= 1/(1-cosx)*sinx + 0=11cosxsinx+0
(chain rule)

= color(green)(sinx/(1-cosx))=sinx1cosx