`intsec^(3)xdx=?`

Explanation

`intsec^(3)xdx=intsecx*sec^(2)xdx`
`=secx*(tanx)-intsecxtanx(tanx)dx" [integrating by parts]"`
`=secxtanx-intsecx(sec^(2)x-1)dx`
`=secxtanx-intsec^(3)xdx+intsecxdx`
`:.2intsec^(2)xdx=secxtanx+log|{:tan((pi)/(4)+(x)/(2)):}|+C`
`orintsec^(3)xdx=(1)/(2)secxtanx+(1)/(2)log|{:tan((pi)/(4)+(x)/(2)):}|+C'`.