Results 1 to 2 of 2

Math Help - trig integral

  1. #1
    Member
    Joined
    Feb 2009
    Posts
    106

    trig integral

    \int\ cos^3xsin2x

    i first split up cos^3x into cosx(1-sin^2(x)) and i said sin2x= 2sinxcosx. this is apparently the correct approach, but when i did it on my quiz today, i ended up getting -1/10 cos^5x +c  instead of -2/5 cos^5x +c . the latter is the correct answer.. can someone help me find my mistake?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member
    Joined
    Jan 2009
    Posts
    108
    convert sin(2x) into 2sin(x)cos(x) and then you should be ready to integrate using the power rule with u substitution where u = cos(x)
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] Trig Integral
    Posted in the Calculus Forum
    Replies: 2
    Last Post: January 1st 2011, 11:00 AM
  2. trig integral 1/(1-sin(x)cos(x))
    Posted in the Calculus Forum
    Replies: 5
    Last Post: January 26th 2010, 08:29 AM
  3. trig integral
    Posted in the Calculus Forum
    Replies: 5
    Last Post: April 24th 2009, 04:35 PM
  4. trig integral
    Posted in the Calculus Forum
    Replies: 4
    Last Post: April 11th 2009, 07:48 PM
  5. Another trig integral
    Posted in the Calculus Forum
    Replies: 1
    Last Post: February 5th 2009, 09:50 PM

Search Tags


/mathhelpforum @mathhelpforum