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Math Help - UNIT CIRCLE question!

  1. #1
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    UNIT CIRCLE question!

    How can you explain that
    sin(180-θ)=sinθ
    using the unit circle??
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  2. #2
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    Re: UNIT CIRCLE question!

    Quote Originally Posted by laurettarosa View Post
    How can you explain that
    sin(180-θ)=sinθ
    using the unit circle??
    UNIT CIRCLE question!-clipboard01.jpg

    Think about a line that goes from the center of the unit circle to it's perimeter and makes some angle \theta with the x axis.

    The sine of \theta is the y coordinate of the intersection of that line and the unit circle because it's radius is 1.

    Now what does 180-\theta do. It reflects this line about the y axis. The x coordinate of the intersection with the unit circle is multiplied by -1, and the y coordinate remains the same. Thus the sine of \theta remains the same.
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  3. #3
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    Re: UNIT CIRCLE question!

    Thanks so much!!
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