Results 1 to 3 of 3

Math Help - Surface Area using the integral

  1. #1
    Newbie
    Joined
    Oct 2009
    Posts
    10

    Surface Area using the integral

    let f(x)=sinx fpr 0 to pi. Find the surface Area of the solid formed by revolving about the x-axis.

    Now i know that it is the integral of 2pi Y ds which becomes 2pi sinx(1+(sinx)^2)^(1/2)

    i just don't know how to integrate it after that. i tried a u sub and that didn't work. if someone could point me in the right direction that'd be great.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Math Engineering Student
    Krizalid's Avatar
    Joined
    Mar 2007
    From
    Santiago, Chile
    Posts
    3,654
    Thanks
    14
    you made a mistake, the integral is actually \int_0^\pi\sin(x)\sqrt{1+\cos^2x}\,dx, put t=\cos x and the remaining integral can be tackled by using trig. or hyperbolic substitution.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Oct 2009
    Posts
    10
    Quote Originally Posted by Krizalid View Post
    you made a mistake, the integral is actually \int_0^\pi\sin(x)\sqrt{1+\cos^2x}\,dx, put t=\cos x and the remaining integral can be tackled by using trig. or hyperbolic substitution.
    Okay that was a really stupid mistake but that makes it waaaayyyy easier to solve. thanks
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] Surface area integral?
    Posted in the Calculus Forum
    Replies: 4
    Last Post: May 17th 2011, 10:46 AM
  2. Surface area integral
    Posted in the Calculus Forum
    Replies: 1
    Last Post: March 1st 2010, 01:50 PM
  3. Surface area integral
    Posted in the Calculus Forum
    Replies: 1
    Last Post: January 17th 2010, 03:39 PM
  4. Surface area integral
    Posted in the Calculus Forum
    Replies: 1
    Last Post: March 11th 2009, 06:40 AM
  5. Surface Area Integral
    Posted in the Calculus Forum
    Replies: 3
    Last Post: May 8th 2008, 01:24 PM

Search Tags


/mathhelpforum @mathhelpforum