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Triangle that has the hypo as √(u^2 +1)

  1. Sep 26, 2013 #1
    1. The problem statement, all variables and given/known data

    If I have a triangle that has the hypo as √(u^2 +1)
    adj as 1 and oppo as u
    I did an integral with trig sub. So I used


    2. Relevant equations

    u = tan(θ)

    3. The attempt at a solution
    At the end of my integral I ended up with an expression (1/4)sin(2θ)
    When I substitute back in to the integral for theta. I will get (1/2)(u/(sqrt(u^2 +1))
    right? How does back sub work if you have 2(theta)
     
  2. jcsd
  3. Sep 26, 2013 #2

    vela

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    Use ##\sin 2\theta = 2 \sin \theta \cos \theta##. You need the trig functions in terms of ##\theta##, not ##2\theta##.
     
  4. Sep 26, 2013 #3
    Always like this? With double angle?
     
  5. Sep 26, 2013 #4

    vela

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    Could you please use complete sentences? I'm not sure what you're asking.
     
  6. Sep 26, 2013 #5
    Nevermind thx
     
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