Final answer:
The signal x(t) = 13sin(120kt+3π/4) is periodic. Assuming k is given in radians per second, the frequency in Hertz is f = 120k/(2π).
Step-by-step explanation:
You asked whether the signal x(t) = 13sin(120kt+3π/4) is periodic and, if so, to list its frequency in Hertz. This signal is indeed periodic. In general, a sine function of the form A sin(ωt + φ) is periodic with a period T = 2π/ω.
The variable ω represents the angular frequency, which is related to the frequency f by the equation ω = 2πf. In your case, the angular frequency ω is 120k, where k needs to be known to determine the frequency. Assuming k is given and is in radians per second, the frequency in Hertz (cycles per second) would be:
f = ω/(2π) = 120k/(2π)