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Math Help - [SOLVED] Trigonometric help 2

  1. #1
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    [SOLVED] Trigonometric help 2

    Use a calculator to find ,to four significant digits , approx. values of the other five trigonometric functions of theta:

    a)cos theta=0.7816 and theta is in the first quadrant

    How to do this question...
    thank you
    Last edited by mj.alawami; January 14th 2009 at 11:55 AM.
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  2. #2
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    i think you would just find theta by using inverse cosine and then substitute it into the other five trignometric functions?
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  3. #3
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    Quote Originally Posted by hmmmm View Post
    i thibk you would just find theta and then substitute it into the other five trignometric functions?
    how to subtitute it to find the value ?
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  4. #4
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    Quote Originally Posted by mj.alawami View Post
    Use a calculator to find ,to four significant digits , approx. values of the other five trigonometric functions of theta:

    a)cos theta=0.7816 and theta is in the first quadrant

    How to do this question...
    thank you
    Hello mj,

    I showed you how to do this in the other post you neglected.

    \cos \theta=0.7816

    \cos \theta = \frac{x}{r}=\frac{0.7816}{1}

    \sec \theta = \frac{1}{0.7816}\approx 1.279

    Thus, \boxed{r = 1} and \boxed{x \approx 0.7816}

    Now find y.

    r^2=x^2+y^2

    1=(0.7816)^2+y^2

    \boxed{y\approx 0.6238}

    Now you have x, y, and r. Go back to your other post and see the appropriate ratios so you can substitute these values in to find sin, tan, csc, and cot.
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