Real quick answers
graph a triangle (lmn) and reflect it over the line y=x to create triangle l’m’n’. describe the transformation using words draw a line segment from point l to the reflecting line, and then draw a line segment from point l’ to the reflecting line. what do you notice about the two line segments you drew? do you think you would see the same characteristic if you drew the line segment connecting m with the reflecting kind and then m’ with the reflecting line? how do you know?