E eng question:?

Can anyone show how to do this:

A sinusoidal current has an RMS value of 7,2 A and a frequency of 60Hz

Calculate the time for the current to increase from zero to 4,8A for the first time.

Calculate the value of the current 1,85 ms after passing through zero in a positive direction

Answer:
Current as a function of time(seconds) is I(t) = I(peak) X Sin(omega X t). Omega is 2 X Pi X frequency(Hz). Therefore I(t) = I(peak) X Sin(377 X t). RMS current is peak current X square root of 2. Therefore 7,2 A RMS Sin peak is 10,18A. I(t) = 4,8 A when 10,18 X Sin(377 X t) = 4,8. At t = 1,85 ms, I(t) = 10,18 X Sin(377 X 1,85/1000)

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