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Unit Circle inequality.

  1. Jan 2, 2007 #1
    This was an exam question I had at the end of 2005 in my uni entrance exams.
    Can you do it?

    Establish the inequality

    [tex] xcosx < sinx < x [/tex] where [tex]0<x<pi/2[/tex] using the unit circle.

    is the tex working?
  2. jcsd
  3. Jan 2, 2007 #2
    This is a classic. Here:

    http://www.csun.edu/~ac53971/courses/math350/xtra_sine.pdf" [Broken]

    The first part of the proof is what you are looking for.

    Edit: Is it a challenge? If so then most people here will be able to do it, this is a very known proof.
    Last edited by a moderator: May 2, 2017
  4. Jan 2, 2007 #3
    That was quick!

    Yes, that's it. Cheers,
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