Question

How do you determine the amplitude and period of the function `y=3cos((pix)/2)`?

Answer 1

You can "read" these information from the numbers in your function, i.e, `3` (multiplying `cos`) and `pi/2` (multiplying `x`):
Amplitude is `3` meaning that your function oscillates between `+3 and -3`;
Period is given using `pi/2` in the form of: `(period)=(2pi)/color(red)(pi/2)=4`.