Results 1 to 5 of 5

Math Help - Arc Length and Surfaces of Revolution

  1. #1
    Member
    Joined
    Jan 2009
    Posts
    100

    Arc Length and Surfaces of Revolution

    Fing the arc length of the graph of the function over the indicated interval.

    y = (x^4)/(8) - (1/(4x^2))

    on interval [1,2]
    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
    I think ya know what the arc-lenght formula is, so post what you've done to verify where you're getting stuck.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Jan 2009
    Posts
    100
    <br />
y'= \frac {1}{2}x^3 - \frac {1}{2x^3} on int [1,2]

    <br />
= \int \sqrt{1+ (\frac {1}{2}x^3 - \frac {1}{2x^3})^2}<br />

    I don't know how to square this and combine it with the 1. I understand how to integrate it from there but, combining this is really stumping me.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Math Engineering Student
    Krizalid's Avatar
    Joined
    Mar 2007
    From
    Santiago, Chile
    Posts
    3,654
    Thanks
    14
    Quote Originally Posted by saiyanmx89 View Post
    <br />
y'= \frac {1}{2}x^3 - \frac {1}{2x^3} on int [1,2]
    Well that's actually a +\frac1{2x^3}. Now, do the algebra in the radicand, what do you get?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member
    Joined
    Jan 2009
    Posts
    100
    <br />
\int \sqrt{1 + \frac{(x^6+1)^2}{4x^6}}

    is this right?
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: October 29th 2010, 06:31 AM
  2. Surfaces
    Posted in the Calculus Forum
    Replies: 1
    Last Post: May 28th 2010, 12:31 PM
  3. Arc Length and Area Surface by revolution
    Posted in the Calculus Forum
    Replies: 13
    Last Post: March 12th 2009, 05:55 PM
  4. Area of surfaces of revolution
    Posted in the Calculus Forum
    Replies: 7
    Last Post: September 11th 2008, 10:41 AM
  5. Surfaces
    Posted in the Geometry Forum
    Replies: 2
    Last Post: February 2nd 2007, 06:34 AM

Search Tags


/mathhelpforum @mathhelpforum