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Math Help - identities and equations?

  1. #1
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    Exclamation identities and equations?

    hi, I know that you need to sub in a trig identity to the equation... but I don't know which one or what to do... I'm so confused.

    sin(2theta) + 4cos(theta) = 0
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  2. #2
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    Quote Originally Posted by [nuthing] View Post
    hi, I know that you need to sub in a trig identity to the equation... but I don't know which one or what to do... I'm so confused.

    sin(2theta) + 4cos(theta) = 0
    use the double angle identity, \sin(2t) = 2\sin{t}\cos{t}, factor and solve.
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  3. #3
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    Quote Originally Posted by skeeter View Post
    use the double angle identity, \sin(2t) = 2\sin{t}\cos{t}, factor and solve.
    yeah, but how?
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  4. #4
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    Quote Originally Posted by [nuthing] View Post
    yeah, but how?
    Well can you factor 2xy-4y~?
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  5. #5
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    Quote Originally Posted by [nuthing] View Post
    yeah, but how?
    1. Use the double angle formula
    2. Factor
    3. Solve

    1. sin(2t) + 4cos(t) = 0 becomes
    2sin(t)cos(t) + 4cos(t) = 0
    2. Take out the greatest common factor
    3. Set each factor equal to zero, using the "zero product property" (field)
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