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Math Help - Finding Angles(Factor Formulae)

  1. #1
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    Finding Angles(Factor Formulae)

    Find all angles between 0 and \pi for which 4cos\frac{A}{2}cosAsin\frac{5A}{2}=0
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  2. #2
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    Hello Punch
    Quote Originally Posted by Punch View Post
    Find all angles between 0 and \pi for which 4cos\frac{A}{2}cosAsin\frac{5A}{2}=0
    Given that
    4\cos\frac{A}{2}\cos A\sin\frac{5A}{2}=0
    any of these three factors could be zero. So you must solve:
    \cos\frac{A}{2}=0
    and
    \cos A=0
    and
    \sin\frac{5A}{2}=0
    Can you do that?

    Grandad
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  3. #3
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    Quote Originally Posted by Grandad View Post
    Hello PunchGiven that
    4\cos\frac{A}{2}\cos A\sin\frac{5A}{2}=0
    any of these three factors could be zero. So you must solve:
    \cos\frac{A}{2}=0
    and
    \cos A=0
    and
    \sin\frac{5A}{2}=0
    Can you do that?

    Grandad
    Never Thought it to be like this, thanks
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  4. #4
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    Just a little question if <br />
\sin\frac{5A}{2}=0<br />
, then in what quadrants does A lies in? Does zero means that it is positive or negative?

    Edit: Found out that zero is neutral and it belongs to all quadrant.
    Last edited by Punch; January 20th 2010 at 02:33 AM.
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