To determine the congruence of the rectangles, after rotating the rectangle in Quadrant III (the first rectangle) 90 degrees clockwise about the origin, the next step would be to translate the rotated rectangle to align it with the coordinates of the rectangle in Quadrant I.
This translation process would involve moving the rotated rectangle along the coordinate plane until its vertices match the corresponding vertices of the rectangle in Quadrant I. Specifically, you would find the required horizontal and vertical shifts needed to position the rotated rectangle over the rectangle defined by the coordinates in Quadrant I.
Once the rectangles are aligned, you can then compare their dimensions (length and width) to confirm that they are congruent.