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Math Help - fundimental identies

  1. #1
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    fundimental identies

    use the fundimental identies to find the value of the trigonomic function.
    sin 0, if cos 0 = 2/3 and 0 is in quadrant IV

    1. -3/2
    2. (3 square root 7)/7
    3. 5/4
    4. -( square root 5)/3
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  2. #2
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    Quote Originally Posted by wenatchee View Post
    use the fundimental identies to find the value of the trigonomic function.
    sin 0, if cos 0 = 2/3 and 0 is in quadrant IV

    1. -3/2
    2. (3 square root 7)/7
    3. 5/4
    4. -( square root 5)/3
    Is your 0 supposed to represent \theta?

    Make use of the Pythagorean Identity:

    \cos^2{\theta} + \sin^2{\theta} = 1

    \left(\frac{2}{3}\right)^2 + \sin^2{\theta} = 1

    \frac{4}{9} + \sin^2{\theta} = 1

    \sin^2{\theta} = \frac{5}{9}

    \sin{\theta} = \pm \frac{\sqrt{5}}{3}.


    Since \theta is in Quadrant 4, we know \sin{\theta}< 0.


    So \sin{\theta} = -\frac{\sqrt{5}}{3}.
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  3. #3
    No one in Particular VonNemo19's Avatar
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    Quote Originally Posted by wenatchee View Post
    use the fundimental identies to find the value of the trigonomic function.
    sin 0, if cos 0 = 2/3 and 0 is in quadrant IV

    1. -3/2
    2. (3 square root 7)/7
    3. 5/4
    4. -( square root 5)/3
    I take it that by "0", you mean \theta.

    So...

    \sin\theta=\sqrt{1-\cos^2\theta}

    Can you see what needs to be done?
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  4. #4
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    Quote Originally Posted by VonNemo19 View Post
    I take it that by "0", you mean \theta.

    So...

    \sin\theta=\sqrt{1-\cos^2\theta}

    Can you see what needs to be done?
    Beat ya
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  5. #5
    No one in Particular VonNemo19's Avatar
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    Quote Originally Posted by Prove It View Post
    Beat ya
    You did indeed, you scoundrel! Until we meet again, Proveit!

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  6. #6
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    slowly

    Thanks I left my book and calculator at school and missed this whole section due to swine flu.
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  7. #7
    No one in Particular VonNemo19's Avatar
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    Quote Originally Posted by wenatchee View Post
    Thanks I left my book and calculator at school and missed this whole section due to swine flu.
    Where you from? In the US, I mean.
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  8. #8
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    how do you get all the math symbols
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  9. #9
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    malaga washington
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  10. #10
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    You get the math symbols using LaTeX.


    Go to the LaTeX help sub-forum on this site, and read through the tutorials.
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  11. #11
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    Where in Austrailia are you from? I used to live in Sydney for about 6 months.
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  12. #12
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    Melbourne, but I am currently living in Mildura.
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