Find the integrals of the functions.

tan4x = tan2x.tan2x

= (sec2x-1) tan2x


= sec2x tan2x- tan2x


= sec2x tan2x- (sec2x-1)


= sec2x tan2x- sec2x+1


Now,


⇒


Now, let tanx = t


=> sec2x dx =dt


⇒


⇒


20