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Math Help - Algebraic Trigonometry

  1. #1
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    Algebraic Trigonometry

    How do you obtain an answer in radians from a special triangle? For example how would you get the answer for this question? (The answer is written but I don't know how to get it). So far I have used the CAST method so I know it is in quadrants 3 and 4. I also know that it is a 30 degree triangle.

    sinx= -1/2 Domain: 0<x<2(pi)
    x=7(pi)/6, 11(pi)/6


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    Last edited by leuge121; June 3rd 2013 at 05:35 PM.
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  2. #2
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    Re: Algebraic Trigonometry

    If you know your special triangles, you can convert angles to radians using the fact that  \displaystyle 360^{\circ} = 2\pi ^{C} \implies 1^{\circ} = \frac{\pi}{180}^{C}.
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  3. #3
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    Re: Algebraic Trigonometry

    How would you do it using the unit circle?
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    Re: Algebraic Trigonometry

    Once you know the first quadrant's angle \displaystyle \begin{align*} \theta \end{align*}, then the angle in Q2 is \displaystyle \begin{align*} \pi - \theta \end{align*}, the angle in Q3 is \displaystyle \begin{align*} \pi + \theta \end{align*} and the angle in Q4 is \displaystyle \begin{align*} 2\pi - \theta \end{align*}.
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  5. #5
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    Re: Algebraic Trigonometry

    Ahh ok thanks mate.
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