Question

How do you find the amplitude and period of a function `y=3 cos x`?

Answer 1

The amplitude is 3, the period is 2`pi` and (if you cared) the phase change is (0, 0).

Explanation:

The equation can be written as `a cos(b(x-c)) + d`. For sin and cos (but not tan) `|a|` is the amplitude, `(2pi)/|b|` is the period, and `c` and `d` are the phase shifts. `c` is the phase shift to the right (positive `x` direction) and `d` is the phase shift up (positive `y` direction). Hope this helps!