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Homework Help: Calc II: Help Solving this Integral

  1. Jun 18, 2012 #1
    1. The problem statement, all variables and given/known data

    [itex]\int \frac{\sqrt{9 - x^2}}{x} dx[/itex]

    2. The attempt at a solution

    x = 3sin(u)
    dx = 3cos(u)du
    u = arcsin(x/3)

    [itex]\int \frac{3\sqrt{cos(u)^2}}{3sin(u)} 3cos(u)du[/itex]

    [itex]3 \int \frac{cos(u)}{sin(u)} cos(u)du[/itex]

    Don't really see anywhere to go from here. Apologies if the work is hard to follow, I cut out a few steps because inputting equations is a real pain in my opinion.
  2. jcsd
  3. Jun 18, 2012 #2


    Staff: Mentor

    Write cos2(u) as 1 - sin2(u), and then split into two integrals.
  4. Jun 18, 2012 #3
    Ah! Thank you, I'll give it a try
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