Fourier Transform in the Form of Dirac-Delta Function

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The discussion focuses on finding the Fourier transform X(f) of the given function x(t)=8cos(70πt)+4sin(132πt)+8cos(24πt) using Dirac delta functions. The relevant equations for transforming cosine and sine functions into the frequency domain are presented. The solution is derived, resulting in X(f) expressed as a combination of delta functions at specific frequencies. The final simplified form includes terms for each frequency component, confirming the calculations are correct. The discussion concludes with an affirmation of the solution's clarity and correctness.
Captain1024
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Homework Statement


Given x(t)=8cos(70\pi t)+4sin(132\pi t)+8cos(24\pi t), find the Fourier transform X(f) in the form of \delta function.

Homework Equations


X(f)=\int ^{\infty}_{-\infty}x(t)e^{-j\omega _0t}dt
cos(\omega t)=\frac{e^{j\omega t}+e^{-j\omega t}}{2}
sin(\omega t)=\frac{e^{j\omega t}-e^{-j\omega t}}{2j}
\int ^{\infty}_{-\infty}cos(\omega _0t)e^{-j\omega t}dt=\frac{\pi}{2}(\delta (\omega +\omega _0)+\delta (\omega -\omega _0))
\int ^{\infty}_{-\infty}sin(\omega _0t)e^{-j\omega t}dt=\frac{\pi}{j2}(\delta (\omega +\omega _0)-\delta (\omega -\omega _0))

The Attempt at a Solution


X(f)=\frac{8\pi}{2}(\delta (\omega +70\pi)+\delta (\omega -70\pi))+\frac{4\pi}{j2}(\delta (\omega +132\pi)-\delta (\omega -132\pi))+\frac{8\pi}{2}(\delta (\omega +24\pi)+\delta (\omega -24\pi))

Simplifying: X(f)=4\pi (\delta (\omega +70\pi)+\delta (\omega -70\pi))+\frac{2\pi}{j} (\delta (\omega +132\pi)-\delta (\omega -132\pi))+4\pi (\delta (\omega +24\pi)+\delta (\omega -24\pi))
 
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All clear, Captain!
(You could changew +1/2j to -j/2 but that would be quibbling!)
Nice work.
 

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