Find the mid-line of the graph.
What is the vertical shift?
What is the amplitude?
What is the easiest shift for the sine?
What is the easiest shift for the cosine?
Flip it upside down.
Horizontal shift to the left π/2.
Use the eTool below to visualize this problem.
Click on the link to the right to view the full version of the eTool: PCT 4-88 eTool