Identify all the complex frequencies present in these real functions: (a) \((2e^{?100t} + e^{?200t} )\ sin\ 2000t\) ; (b) \((2 ? e^{?10t})\ cos(4t + \phi)\); (c) \(e^{?10t}\ cos\ 10t\ sin\ 40t\).
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Textbook Solutions for Engineering Circuit Analysis
Question
Evaluate the following expressions at t = 0:
(a) \(+\int _{-\infty} ^{\infty}\ 2 \delta(t-1)\ dt\); (b) \(\frac{\int _{-\infty} ^{+\infty}\ \delta (t + 1)\ dt}{u(t + 1)}\); (c) \(\frac{\sqrt{3\ \int _{-\infty} ^{+\infty}\ \delta (t - 2)\ dt}}{[u(1 - t)]^3} - \sqrt{u(t + 2)}\); (d) \([\frac{\int _{-\infty} ^{+\infty}\ \delta (t - 1)\ dt}{\int _{-\infty} ^{+\infty}\ \delta (t + 1)\ dt}|]^2\).
Solution
The first step in solving 14 problem number 65 trying to solve the problem we have to refer to the textbook question: Evaluate the following expressions at t = 0:(a) \(+\int _{-\infty} ^{\infty}\ 2 \delta(t-1)\ dt\); (b) \(\frac{\int _{-\infty} ^{+\infty}\ \delta (t + 1)\ dt}{u(t + 1)}\); (c) \(\frac{\sqrt{3\ \int _{-\infty} ^{+\infty}\ \delta (t - 2)\ dt}}{[u(1 - t)]^3} - \sqrt{u(t + 2)}\); (d) \([\frac{\int _{-\infty} ^{+\infty}\ \delta (t - 1)\ dt}{\int _{-\infty} ^{+\infty}\ \delta (t + 1)\ dt}|]^2\).
From the textbook chapter Complex Frequency and the Laplace Transform you will find a few key concepts needed to solve this.
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