When two lines are parallel, the perpendicular distance between them is the same all through the way and the angles formed between the parallel lines and the perpendicular ones joining them is equal to 90 degree.
Example of this is the square or the rectangle as shown below:
AB || BC and both AD and BC are perpendicular on the two lines.
Accordingly, the two perpendicular lines are equal
Based on this, the ratio of PR and QS is 1:1