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Math Help - Find Exact Value of SinB

  1. #16
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    Re: Find Exact Value of SinB

    Quote Originally Posted by JohnTerry View Post
    Thanks again, but how \cos{\beta} = (-1)\cos{\alpha} + (0)\sin{\alpha} = -\cos{\alpha}
    = \cos{\beta} = \cos{\pi}\cos{\alpha} + \sin{\pi}\sin{\alpha}
    \pi is on the unit circle so there are exact values for \sin(\pi) and \cos(\pi). What level of trig are you at if you don't mind me asking? The unit circle is pretty elementary in trig.

    What does (-1) and (0) mean?
    Don't read too much into it: they're numbers.
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  2. #17
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    Re: Find Exact Value of SinB

    Quote Originally Posted by JohnTerry View Post
    Thanks again, but how \cos{\beta} = (-1)\cos{\alpha} + (0)\sin{\alpha} = -\cos{\alpha}
    = \cos{\beta} = \cos{\pi}\cos{\alpha} + \sin{\pi}\sin{\alpha}


    What does (-1) and (0) mean?
    \cos{\pi} = -1

    \sin{\pi} = 0

    you should know these from your unit circle values ...

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  3. #18
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    Re: Find Exact Value of SinB

    Quote Originally Posted by JohnTerry View Post
    Thanks again, but how \cos{\beta} = (-1)\cos{\alpha} + (0)\sin{\alpha} = -\cos{\alpha}
    = \cos{\beta} = \cos{\pi}\cos{\alpha} + \sin{\pi}\sin{\alpha}


    What does (-1) and (0) mean?
    Sorry, but it's time you made an effort and started thinking. Go back, review the thread, read the link, consider your class notes. There's been enough spoon-feeding for the time being.
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