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Unit Circle

The unit circle is the circle whose centre is at the origin and whose radius is one. The trigonometric functions cosine and sine may be defined on the unit circle as follows. If (x, y) is a point of the unit circle, and if the ray from the origin (0, 0) to (x, y) makes an angle q from the positive x-axis, (where counterclockwise turning is positive), then:

q = x
sin q = y

Trig 2 PowerPoint File 0.5Mb

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