What is the amplitude and period of y=3sin(5x)?

Amplitude of a periodic function is the maximum height it reaches above the centre line (or the lowest). This expressed in the equation as '3'. If the 3 was not there, then the sin wave would have an amplitude of 1, however the 3 multiplies the height.

The period is the distance for the periodic function to return to its original position. For example, peak to peak. For a standard sin wave, the period is 2(pi). In this function, the '5' is making the period shorter. Therefore, the period would be 2(pi)/5.