a The frequency of the sin(x) depends on the period
If the wave has period = 2pi, then the frequency is 1
The frequency of sin(2x) is 2
The given equation is
[tex]v=520\sin (30t-\frac{5\pi}{4})[/tex]Since the frequency = 2pi/period
Since the period = 2pi/30 = pi/15
Then
[tex]\begin{gathered} F=\frac{2\pi}{\frac{\pi}{15}} \\ F=2\pi\times\frac{15}{\pi} \\ F=2\times15 \\ F=30\text{ HZ} \end{gathered}[/tex]The frequency is 30 Hz
The answer is B
