### Circular Motion

Since the modulus of the complex sinusoid is constant, it must lie on a*circle*in the complex plane. For example,

*counter-clockwise*circular motion along the unit circle in the complex plane as increases, while

*clockwise*circular motion. We may call a complex sinusoid a

*positive-frequency sinusoid*when . Similarly, we may define a complex sinusoid of the form , with , to be a

*negative-frequency sinusoid*. Note that a positive- or negative-frequency sinusoid is necessarily complex.

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Projection of Circular Motion

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Audio Decay Time (T60)