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Homework Help: Stupid brain cramp

  1. Dec 27, 2005 #1
    hey, i need to simplify this, and im having a brain fart:confused: ...can u help me?

    f(x)= cosx(3cos3x) + (sin3x)(-sinx)

    i then have to find f(pi/6), but im hoping i can do that once this is simplified...

  2. jcsd
  3. Dec 27, 2005 #2
    I wonder you made a typo.... is cosx(3cos3x) [tex]\cos(x*3\cos(3x))[/tex] or [tex]\cos(x)*3\cos(3x)[/tex]? Please place braces and it will clarify. But as for f(pi/6), it looks easy in any typo cases, because [tex]\cos(3*\pi/6) = 0, \sin(3*\pi/6) = 1[/tex] :smile:
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