1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Finding an integral

  1. Apr 5, 2008 #1
    1. The problem statement, all variables and given/known data

    I would just like some help on how to find the integral of:
    sin(x) / cos(x)^2

    2. Relevant equations

    integration by parts?
    uv-integral of v(du)

    3. The attempt at a solution
    I tried using integration of parts with u = cos(x)^2 and dv = sin(x) but I just got myself in a bigger mess.

    I noticed that sin(x) / cos(x)^2 was equal to tan(x)sec(x). Not sure if that helps though...

    Help please?!
  2. jcsd
  3. Apr 5, 2008 #2
    I'd go for a substitution.
  4. Apr 5, 2008 #3
    Try the substitution cos(x)^2.
  5. Apr 5, 2008 #4
    what's integral of [(-2*u)/(1-u^2)]/-2


    try to see 1/x connection
    Last edited: Apr 5, 2008
  6. Apr 5, 2008 #5


    User Avatar
    Homework Helper

    [tex]\int \frac{sinx}{cos^2x} dx[/tex]

    [tex]\equiv \int \frac{sinx}{cosx} \times \frac{1}{cosx}dx[/tex]

    What is another way to write [itex]\frac{sinx}{cosx}[/itex]?
    and similarly [itex]\frac{1}{cosx}[/itex]?

    Should be pretty standard after you see it.
  7. Apr 6, 2008 #6
    Got it. Thank you everyone.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook