In this example, the

amplitude`a = 12`, and

`b = 2`, so theperiod= `(2π)/b = (2π)/2 = π`, and

`c=-pi/8`

so the **phase shift** is

`-c/b=-(-pi"/"8)/2=pi/16`

This means we need to move the cosine graph to the
**right** of its normal position (because the displacement is
positive in this example) by `pi/16`.

Without phase shift, the cosine curve will be *y* = 12 cos 2*x* and its graph is as follows:

Now, let's shift it to the right by *π*/16 ≈ 0.1963:

You can see the original cosine curve (in gray) and we have shifted it by `pi/16` to the right to give the required graph of `y = 12 cos (2x − π/8)`, in blue.