Results 1 to 3 of 3

Math Help - polar coordinates

  1. #1
    Junior Member
    Joined
    Mar 2007
    From
    Missouri
    Posts
    54

    polar coordinates

    any one here good with finding area of surface of revolution or arc length in polar coordinate system?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Junior Member
    Joined
    Mar 2007
    From
    Missouri
    Posts
    54
    I finally got one of the problems I was working on. Now stuck on find the length of the curve over the given interval.

    r=8(1+cos theta) [0, 2pi]
    r=8+8 cos theta
    r`=-8 sin theta

    Arc length= 2 \int_0^\pi\sqrt{(8+8~cos\theta)^2+(-8~sin\theta)^2}~d\theta=2\int_0^\pi\sqrt{64+128~co  s\theta+64~cos^2\theta+64~sin^2\theta}~d\theta

    I am stuck at this point.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Senior Member tukeywilliams's Avatar
    Joined
    Mar 2007
    Posts
    307
     2 \int_{0}^{\pi} \sqrt{64 + 128 \cos \theta + 64 \cos^{2} \theta + 64 \sin^{2} \theta} \ d \theta =  2 \int_{0}^{\pi} \sqrt{128(1 + \cos \theta)} \ d \theta  = 2 \sqrt{128} \int_{0}^{\pi} \sqrt{1 + \cos \theta} \ d \theta = 4 \sqrt{128} \sqrt{\cos x +1} \tan \left(\frac{x}{2} \right) .
    Last edited by tukeywilliams; July 25th 2007 at 04:38 PM.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 10
    Last Post: September 24th 2010, 04:33 AM
  2. Replies: 6
    Last Post: February 4th 2009, 12:12 AM
  3. polar coordinates
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: August 30th 2008, 03:33 PM
  4. Polar Coordinates and Polar Graphs
    Posted in the Pre-Calculus Forum
    Replies: 4
    Last Post: October 2nd 2007, 04:44 PM
  5. polar coordinates
    Posted in the Calculus Forum
    Replies: 2
    Last Post: September 5th 2007, 07:07 PM

Search Tags


/mathhelpforum @mathhelpforum