How do you integrate Sinx * Tanxsinxtanx?

1 Answer
Dec 9, 2016

The answer is =ln (∣tanx+secx∣)-sinx +C=ln(tanx+secx)sinx+C

Explanation:

We need, secx=1/cosxsecx=1cosx

cos^2x+sin^2x=1cos2x+sin2x=1

tanx=sinx/cosxtanx=sinxcosx

(tanx)'=sec^2x

(secx)'=tanx secx

intsinxtanxdx=int(sinx*sinxdx)/cosx

=intsecxsin^2xdx

=intsecx(1-cos^2x)dx

=int(secx-cosx)dx=intsecxdx-intcosxdx

For the integral of secx, multiply top and bottom by
(tanx+secx)

intsecxdx=int(secx(tanx+secx)dx)/(tanx +secx)

Let u=tanx +secx

du=(sec^2x+secxtanx)dx

intsecxdx=int(du)/u

=lnu = ln (∣tanx+secx∣)

And finally,

intsinxtanxdx= ln (∣tanx+secx∣)-sinx +C