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Thread: cos identities

  1. November 11th 2009, 05:10 AM #1
    Oasis1993
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    cos identities

    Solve the Equation for A between 0 and 360 inclusive, giving non-exact answers. In each case use trigonometric identities.

    a) cos2A +3 +4cosA=0

    b) 2cos 2A+1+ sinA= 0

    THANKS!
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  2. November 11th 2009, 05:24 AM #2
    mathaddict
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    Quote Originally Posted by Oasis1993 View Post
    Solve the Equation for A between 0 and 360 inclusive, giving non-exact answers. In each case use trigonometric identities.

    a) cos2A +3 +4cosA=0

    b) 2cos 2A+1+ sinA= 0

    THANKS!
    HI

    (1) 2\cos^2 A-1+4\cos A+3=0

    2\cos^2 A+4\cos A+2=0

    \cos^2 A+2\cos A+1=0

    \cos A=-1

    go on ....

    (2) 2(1-\sin^2 A)+1+\sin A =0
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« Trigometric equations. | Exact Solution of the Equation »

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