Revision as of 05:51, 5 September 2008 by Kadafin (Talk)

cos(t-2)

Energy

A time shift should not effect the energy of a function.

$ u = (t-2) $

$ E=\int_{-2}^{2\pi-2}{|cos(u)|^2du} $


$ E=\frac{1}{2}\int_{-2}^{2\pi-2}(1+cos(2(u)))du $


$ E=\frac{1}{2}((u+\frac{1}{2}sin(2(u)))|_{u=-2}^{u=2\pi-2} $


$ E=\frac{1}{2}(2\pi-2 + .378 -(-2 - .378)) $


$ E=\pi $

Power

$ E=\frac{1}{2\pi-0}\int_{-2}^{2\pi-2}{|cos(u)|^2du} $


$ =\frac{1}{2\pi-0} *{\frac{1}{2}}\int_{-2}^{2\pi-2}(1+cos(2u))du $


$ =\frac{1}{4\pi}((u)+\frac{1}{2}sin(2u))|_{u=-2}^{u=2\pi-2} $


$ =\frac{1}{4\pi}(2\pi-2+.378-(-2+.378)) $


$ =\frac{1}{2} $

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