Creation of the Sine Curve

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The following Quicktime animation shows how the sine curve is created. As the dot on the left goes around the unit circle, the dot on the right tracks the y-coordinate of the left dot as the angle x changes. Since sin(x) is, by definition, the y-coordinate of the point on the unit circle corresponding to angle x, it follows that the red curve is the graph of y=sin(x).

If the animation below does not play inside your browser, you can download the movie and play it in Quicktime Player.

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