Results 1 to 3 of 3

Math Help - integration question

  1. #1
    Member
    Joined
    Jul 2007
    Posts
    151

    Question integration question

    the integral from 0 to phi of sin^2 theta d(theta)
    =[theta/2 -sin(2theta)/4 ] from 0 to phi

    Can you explain to me how to arrive the second step ? I don't get it ! Thank you very much.
    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
    I will use x instead of phi.

    \int{sin^{2}(x)}dx

    Use the identity: sin^{2}(x)=\frac{1}{2}(1-cos(2x))

    \frac{1}{2}\int{[1-cos(2x)]}dx=\frac{1}{2}x-\frac{1}{4}sin(2x)+C
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Math Engineering Student
    Krizalid's Avatar
    Joined
    Mar 2007
    From
    Santiago, Chile
    Posts
    3,654
    Thanks
    13
    galactus gave the simplest way, another one could be

    \int\sin^2x~dx=\color{blue}\int\sin{x}\sin{x}~dx

    and apply integration by parts.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. integration question
    Posted in the Calculus Forum
    Replies: 3
    Last Post: April 30th 2011, 07:19 AM
  2. Replies: 6
    Last Post: July 21st 2010, 06:20 PM
  3. Integration Question
    Posted in the Calculus Forum
    Replies: 2
    Last Post: May 20th 2010, 02:59 AM
  4. help with integration question?
    Posted in the Calculus Forum
    Replies: 2
    Last Post: May 19th 2010, 02:49 PM
  5. integration question no. 7
    Posted in the Calculus Forum
    Replies: 2
    Last Post: November 11th 2007, 08:40 AM

Search Tags


/mathhelpforum @mathhelpforum