Math Problem Statement

what is the CTFT of trig(t)

Solution

The Continuous-Time Fourier Transform (CTFT) of the function trig(t)\text{trig}(t) depends on the specific trigonometric function you're referring to. I'll compute the CTFT of some common trigonometric functions:

1. CTFT of cos(ω0t)\cos(\omega_0 t):

cos(ω0t)=ejω0t+ejω0t2\cos(\omega_0 t) = \frac{e^{j\omega_0 t} + e^{-j\omega_0 t}}{2}

Using the CTFT definition:

F{cos(ω0t)}=cos(ω0t)ejωtdt\mathcal{F}\{\cos(\omega_0 t)\} = \int_{-\infty}^{\infty} \cos(\omega_0 t) e^{-j\omega t} dt

This results in two Dirac delta functions:

F{cos(ω0t)}=π[δ(ωω0)+δ(ω+ω0)]\mathcal{F}\{\cos(\omega_0 t)\} = \pi \left[ \delta(\omega - \omega_0) + \delta(\omega + \omega_0) \right]

2. CTFT of sin(ω0t)\sin(\omega_0 t):

sin(ω0t)=ejω0tejω0t2j\sin(\omega_0 t) = \frac{e^{j\omega_0 t} - e^{-j\omega_0 t}}{2j}

By applying the CTFT, we get:

F{sin(ω0t)}=jπ[δ(ω+ω0)δ(ωω0)]\mathcal{F}\{\sin(\omega_0 t)\} = j\pi \left[ \delta(\omega + \omega_0) - \delta(\omega - \omega_0) \right]

Summary:

  • CTFT of cos(ω0t)\cos(\omega_0 t): π[δ(ωω0)+δ(ω+ω0)]\pi [\delta(\omega - \omega_0) + \delta(\omega + \omega_0)]
  • CTFT of sin(ω0t)\sin(\omega_0 t): jπ[δ(ω+ω0)δ(ωω0)]j\pi [\delta(\omega + \omega_0) - \delta(\omega - \omega_0)]

Would you like more details on the Fourier Transform process

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Math Problem Analysis

Mathematical Concepts

Continuous-Time Fourier Transform (CTFT)
Trigonometric Functions
Signal Processing

Formulas

\(\mathcal{F}\{\cos(\omega_0 t)\} = \pi [\delta(\omega - \omega_0) + \delta(\omega + \omega_0)]\)
\(\mathcal{F}\{\sin(\omega_0 t)\} = j\pi [\delta(\omega + \omega_0) - \delta(\omega - \omega_0)]\)

Theorems

Fourier Transform Properties
Dirac Delta Function

Suitable Grade Level

Undergraduate Level