Final answer:
The midline of the equation y = 2(sin(3x) - 2) is the horizontal line y = -2, which represents the average value of the function's maximum and minimum after the vertical shift.
Step-by-step explanation:
The equation of the midline for the trigonometric function y = 2(sin(3x) - 2) can be found by looking at the vertical shift of the sine wave in the equation. A midline for a trigonometric function is a horizontal line that represents the average value of the maximum and minimum values of the function. Since the sine function's maximum and minimum values are 1 and -1 respectively, and the function is given as y = 2(sin(3x) - 2), the midline is affected by the vertical shift of -2. Therefore, the midline will be the horizontal line y = -2, which is the constant term in the given equation.