Final answer:
The midline of the graph is y = -3.9.
Step-by-step explanation:
The midline of a trigonometric function is the horizontal line about which the function oscillates.
In the given graph, the minimum point is at (2,-0.9) and the amplitude is 3.
Since the minimum point is below the midline, we can determine the midline by subtracting the amplitude from the minimum y-value.
Therefore, the midline is given by the equation:
y = -0.9 - 3 = -3.9