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Math Help - Having trouble solving 4*(1+ sin theta) = cos^2 theta

  1. #1
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    Having trouble solving 4*(1+ sin theta) = cos^2 theta

    Hello all!

    Could someone please explain to me how to get started solving this equation? 4*(1+ sin theta) = cos^2 theta
    I am really at a loss.

    Thank you thank you!
    ~Nikki
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  2. #2
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    Re: Having trouble solving 4*(1+ sin theta) = cos^2 theta

    If you replace \cos^2\theta with 1-\sin^2\theta, then you'll get a quadratic equation in \sin\theta.
    Last edited by emakarov; March 25th 2012 at 12:21 PM.
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  3. #3
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    Re: Having trouble solving 4*(1+ sin theta) = cos^2 theta

    Quote Originally Posted by ansulli2 View Post
    Hello all!

    Could someone please explain to me how to get started solving this equation? 4*(1+ sin theta) = cos^2 theta
    I am really at a loss.

    Thank you thank you!
    ~Nikki
    WA , click "show steps"
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  4. #4
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    Re: Having trouble solving 4*(1+ sin theta) = cos^2 theta

    Thank you thank you! So I worked through the problem and I got two solutions -1 and -3, which means on the unit circle only -1 is a correct solution. Right?

    ~Nikki
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  5. #5
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    Re: Having trouble solving 4*(1+ sin theta) = cos^2 theta

    Quote Originally Posted by ansulli2 View Post
    So I worked through the problem and I got two solutions -1 and -3, which means on the unit circle only -1 is a correct solution. Right?
    Yes, and then you need to solve \sin\theta=-1.
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  6. #6
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    Re: Having trouble solving 4*(1+ sin theta) = cos^2 theta

    Quote Originally Posted by ansulli2 View Post
    Thank you thank you! So I worked through the problem and I got two solutions -1 and -3, which means on the unit circle only -1 is a correct solution. Right?

    ~Nikki
    \sin{\theta} = -1

    remember you're solving for \theta ...
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  7. #7
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    Re: Having trouble solving 4*(1+ sin theta) = cos^2 theta

    Thanks all of you, that really helped and now I can work on the rest of the HW problems with a LOT less confusion ^_^

    ~Nikki
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