We'll now explain what the function means and the terms therein.
Midline of 4: This means that the graph will oscillate over y = 4. We attach this to the function by adding 4.
Amplitude of 2: This means that the graph will have a maximum upward/downward displacement of 2. We attach this to the function by multiplying 2 to the cos function.
Period of 3/4: This means that the distance on the x axis between troughs and crests is 3/4. This is added to the function by inverting and multiplying by 2pi. All these while getting its cosine.
