Results 1 to 2 of 2

Math Help - two calculus trig integral problems!

  1. #1
    Member
    Joined
    Nov 2008
    From
    MD
    Posts
    165

    two calculus trig integral problems!

    integrate tan^2(3x)sec^4(3x)dx

    integrate (1+sinx)/(cos^2 x) dx
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Eater of Worlds
    galactus's Avatar
    Joined
    Jul 2006
    From
    Chaneysville, PA
    Posts
    3,001
    Thanks
    1
    \int tan^{2}(3x)sec^{4}(3x)dx

    Let u=3x, \;\ \frac{du}{3}=dx

    \frac{1}{3}\int tan^{2}(u)sec^{4}(u)du

    Rewrite by using the identity sec^{2}(u)=tan^{2}(u)+1

    \frac{1}{3}\int sec^{2}(u)tan^{2}(u)du+\frac{1}{3}\int tan^{4}(u)sec^{2}(u)du

    Now, a simple sub and it works out well to finish.

    Let w=tan(u), \;\ dw=sec^{2}(u)du

    Then, resub.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: June 25th 2010, 11:41 PM
  2. Replies: 7
    Last Post: April 15th 2010, 09:12 PM
  3. Calculus Integral Problems
    Posted in the Calculus Forum
    Replies: 3
    Last Post: March 15th 2009, 04:43 PM
  4. Replies: 1
    Last Post: June 23rd 2008, 10:17 AM
  5. Replies: 2
    Last Post: May 17th 2006, 06:33 AM

Search Tags


/mathhelpforum @mathhelpforum