We know that,
color(red)((1)sin^2theta+ cos^2theta=1(1)sin2θ+cos2θ=1
color(blue)((2)1/costheta=sectheta and sintheta/costheta=tantheta(2)1cosθ=secθandsinθcosθ=tanθ
color(violet)((3)intsec^2xdx=tanx+c(3)∫sec2xdx=tanx+c
color(violet)((4)intsecxtanxdx=secx+c(4)∫secxtanxdx=secx+c
Here,
I=int1/(1+sinx)dx=int((1-sinx))/((1+sinx)(1-sinx))dxI=∫11+sinxdx=∫(1−sinx)(1+sinx)(1−sinx)dx
=>I=int(1-sinx)/(1-sin^2x)dx⇒I=∫1−sinx1−sin2xdx
=int(1-sinx)/cos^2xdx...tocolor(red)(Apply(1)
=int[1/cos^2x-sinx/cos^2x]dx
=int[sec^2x-secxtanx]dx...tocolor(blue)(Apply(2)
Using , color(violet)((3) and (4), we get
I=tanx-secx+c