What is the integral of int secx/tan^2x dxsecxtan2xdx?

1 Answer
Jun 14, 2018

-cscx+Ccscx+C

Explanation:

Let's rewrite the integrand:

intsecx/tan^2xdx=int(1/cosx)/(sin^2x/cos^2x)dx=intcosx/sin^2xsecxtan2xdx=1cosxsin2xcos2xdx=cosxsin2x

Here, recognize that intcosx/sin^2xdx=intcosx/sinx1/sinxdx=intcotxcscxdx=-cscx+Ccosxsin2xdx=cosxsinx1sinxdx=cotxcscxdx=cscx+C.

Another way we can solve intcosx/sin^2xdxcosxsin2xdx is by letting u=sinxu=sinx so du=cosxdxdu=cosxdx. Then,

intcosx/sin^2xdx=intu^-2du=-u^-1+C=-1/sinx+C=-cscx+Ccosxsin2xdx=u2du=u1+C=1sinx+C=cscx+C.