# Homework Help: Integral of sec3xtan3xdx

1. May 13, 2010

### apiwowar

integral of sec3xtan3xdx

i tried to start this by rewriting secx as 1/cosx and that got me the integral of sin2x/cos6xdx

after that i tried a regular substitution but that didnt work since it doesnt take care of the sin3x on top

kinda stuck on where to go
any help?

2. May 13, 2010

### gabbagabbahey

Re: integral

Hint: $\sin^3(x)=\sin(x)[1-\cos^2(x)]$

3. May 13, 2010

### physicsman2

Re: integral

I would try: sec2x(sec x)(tan2x)(tan x)

4. May 13, 2010

### apiwowar

Re: integral

first guys idea worked, thanks

5. May 13, 2010

### thrill3rnit3

Re: integral

tan2x = sec2x-1

6. May 13, 2010

### physicsman2

Re: integral

I know, just showing you another way of going about it, with thrill3rnit3 giving you a huge hint on how to go about it.