Question

The current through a circuit is given by i = 56.4 sin (754t)
A, where t is in seconds. What is the rms current, and what
is the frequency of the ac source?

Answer 1

$I_{rms}=0.707I_m=0.707\cdot56.4\approx40(A)$

$754=2\pi\nu\to \nu=\frac{754}{2\cdot3.14}=120(Hz)$