The even and odd components of the signal x(t) = e-2t cos t are respectively.

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ESE Electronics Prelims 2021 Official Paper
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  1. cos 2t cos t and -sin 2t cos t
  2. sinh 2t sin t and -cosh 2t cos t
  3. cos 2t sin t and -sin 2t cos t
  4. cosh 2t cos t and -sinh 2t cos t

Answer (Detailed Solution Below)

Option 4 : cosh 2t cos t and -sinh 2t cos t
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Detailed Solution

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Concept:

if x(t) is given signal then,

Even signal of x(t) = \(\frac{x(t)+x(-t)}{2}\)

&

odd signal of x(t) =\(\frac{x(t)-x(-t)}{2}\)

Solution:

Here,

x(t) = e-2t cos t 

Even signal of x(t) = \(\frac{x(t)+x(-t)}{2}\)

\(=\frac{e^{-2t} \space cos(t)+e^{-2(-t)} \space cos(-t)}{2}\)

\(=\frac{e^{-2t} \space cos(t)+e^{2t} \space cos(t)}{2}\)

\(= cos(t)\frac{(e^{-2t} \space+e^{2t}) }{2}\)

\(= cos(t)cosh(2t)\)

&

odd signal of x(t) =\(\frac{x(t)-x(-t)}{2}\)

\(=\frac{e^{-2t} \space cos(t)-e^{-2(-t)} \space cos(-t)}{2}\)

\(=\frac{e^{-2t} \space cos(t)-e^{2t} \space cos(t)}{2}\)

\(= cos(t)\frac{(e^{-2t} -e^{2t}) }{2}\)

\(=- cos(t)\frac{(e^{2t} -e^{-2t}) }{2}\)

\(= -cos(t)sinh(2t)\)

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