1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Trig sub

  1. Oct 21, 2008 #1
    1. The problem statement, all variables and given/known data

    Integral of sqrt(1-x^2) dx

    I subbed in sin(Theta) for x, and did my work and got the integral down to: cos(Theta)^2 dTheta.

    The problem I am having is integrating cos(Theta)^2. I could use a half angle formula, but the problem is I have to rewrite theta in terms of x, and if I use have angle I end up with Cos(2Theta), which I don't know how to convert back in to x. Please help.
  2. jcsd
  3. Oct 21, 2008 #2

    Found out the trig property I needed.

    sin(2x) = 2sin(x)cos(x)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Trig sub
  1. Trig sub (Replies: 3)

  2. Very Difficult Trig Sub? (Replies: 16)