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Stuck on a problem!

  1. Jan 30, 2005 #1
    The problem is:
    Find the area of the surface of revolution generated by revolving the curve
    e^(8θ), 0≤θ≥½π around the y-axis.

    θ= Theta
    ½π= 1/2*pi
    sqrt= sqare root
    ² = squared

    Here's my work:
    ds = sqrt( (e^(8θ))² + (e^(8θ))² )dθ
    dθ = (e^(8θ)sqrt(2)
    x = rcos(θ)= e^(8θ)cos(θ)
    A = 2*½π*sqrt(2)*integral of (e^(16θ)cos(θ)) between 0 and ½π
    I solved the integral and I got
    2*½π*(2)/257*(e^(8θ)-16))

    When I plugged the answer online, I got it wrong. Can someone please figure out what's wrong?
     
    Last edited: Jan 31, 2005
  2. jcsd
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