Answer: RR' || SS'
Step-by-step explanation:
Given: The image of trapezoid PQRS after a reflection across is trapezoid P'Q'R'S'.
We know that reflection is an isometry, and points of original shape and the image are equidistant from the line of reflection and the lines created by joining the corresponding points is perpendicular to the line of reflection.
Hence, when we join R and R' or S and S' [corresponding points] , then both the lines will perpendicular to the line of reflection.
Thus, it implies that both the lines have same slope.
Therefore, they are parallel. [because if two lines have same slope then they are parallel]
Hence, RR' || SS'
