Question

How do you determine the amplitude of `y= 5 sin x` and `y= 3 cos x`?

Answer 1

Both `sin(x) " and " cos(x)` have a Range of
`[-1,+1]`

`y=5sin(x)`
maps the points of `sin(x)` into a stretched Range of
`[-5,+5]`
and thus an amplitude of `5`.

Similarly
`y=3cos(x)`
has an amplitude of `3`