Answer:
D, y = cos(x -π/2)
Explanation:
When the cosine function is shifted right by π/2 units, it looks like the sine function. That is what we have here. To shift f(x) to the right, replace x by x-(amount of shift). Here, this means the graph is described by ...
y = 2cos(x -π/2)
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The vertical scale factor is 2 on the graph and in all answer choices.