(→Energy) |
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==Energy== | ==Energy== | ||
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| + | According to formula of Energy of a singal,we can get: | ||
<math>E=\int_0^{2\pi}{|2cos(t)|^2dt}</math> | <math>E=\int_0^{2\pi}{|2cos(t)|^2dt}</math> | ||
Revision as of 15:43, 3 September 2008
Signal
$ y(t)=2cos(t) $
Energy
According to formula of Energy of a singal,we can get:
$ E=\int_0^{2\pi}{|2cos(t)|^2dt} $
$ =\int_0^{2\pi}{(2(2cos(t)^2-1)+2)dt} $
$ =\int_0^{2\pi}{2+cos(2t))dt} $
$ =(2t+sin(2t))|_{t=0}^{t=2\pi} $
$ =(4\pi+0-0-0) $
$ =(4\pi) $
