Sine & Cosine Curves

I'm going to find the Amplitude and period of this function and sketch it's graph.
y=4 cos 2x
The Amplitude(A) is 4 because the number in front of either cos/sin is the A
The period is found by: 2times pie divided by B, which  equals pie(3.14...) because the twos cancel.

Now, To sketch the graph one must do the following steps:

1. Determine the general curvature of the equation; for this equation it will go something like this:(This being the graph in blue)

2.  Next find the period, which we already know is pie

3. Find the amplitude which we also already know is 4.

4/5/6. multiply each point by the number in front of x

0 = 0

    pie/2 = pie/4

pie = pie/2

3*pie/2 = 3*pie/4

two*pie = pie

There is no step 6 in this problem, so on to step 7, which is to graph the equation

Once that is done, you should get this as a graph: