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Integration help please [solved]

  1. Feb 7, 2010 #1
    1. The problem statement, all variables and given/known data

    [tex]\int \frac{1}{\sqrt{a^{2} + x^{2}}}[/tex]

    2. Relevant equations

    3. The attempt at a solution

    I got:

    [tex]\int \frac{1}{\sqrt{a^{2} + x^{2}}} = \sqrt{c} \ast \int \frac{1}{\sqrt{c \ast{x^{2}} + 1}} [/tex]

    [tex] \frac{1}{a^{2}} = c [/tex]

    NEVERMIND! I got it: I couldn't remember the integral of arcsin..
    so it's

    [tex] \frac{1}{a} = c [/tex]

    [tex] c \ast \int \frac{1}{\sqrt{c \ast{x^{2}} + 1}}

    = c \ast arcsin(cx) /c [/tex]
    Last edited: Feb 7, 2010
  2. jcsd
  3. Feb 8, 2010 #2

    This is not an arcsine integral. :redface:
    Try [tex]x=a \,\ tan(\theta)[/tex].
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