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Math Help - C3 identity issue!

  1. #1
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    C3 identity issue!

    Can someone please direct me in the correct identities to use here, really stuck!

    given that 5sec^2x + 3tan^2x =9, find the possible values of sin x.

    Thanks!
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  2. #2
    MHF Contributor MarkFL's Avatar
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    Re: C3 identity issue!

    Multiply through by \cos^2(x) then apply the Pythagorean identity to get a quadratic in \sin^2(x).
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  3. #3
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    Re: C3 identity issue!

    Knowing that: tan^2x + 1 = sec^2x, sec^2x = 1/cos^2x and also sin^2x + cos^2x = 1, is what is required to answer this question.
    More specifically begin by getting everything in terms of sin x and cos x and hopefully it will become much easier to manipulate.
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  4. #4
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    Re: C3 identity issue!

    C3 identity issue!-trigonometric-value.png
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