Final answer:
When a figure above the line y=-1 is reflected across the line y=-1 and then reflected across the line y=-5, the result is the same as not doing any reflection at all. The slope of the equivalent translation vector is zero and the magnitude is also zero.
Step-by-step explanation:
When a figure above the line y=-1 is reflected across the line y=-1, it remains unchanged because the line of reflection is the same as the line of symmetry. Therefore, reflecting the figure across the line y=-1 twice is equivalent to not doing any reflection at all.
The slope of a horizontal line is always zero because there is no change in the y-coordinate for any change in the x-coordinate. Since the line y=-5 is a horizontal line, the slope of the equivalent translation vector is zero.
The magnitude of a translation vector is the distance it moves from its original position. In this case, since the figure does not move at all, the magnitude of the equivalent translation vector is zero.