there are given are two rotations: $R_1$ and $R_2$, and a line segment $AB$. the image of $R_1R_2(AB)$ is a line segment that is parallel to the line segment $R_2R_1(AB)$.
my kindly request is to the reason they are parallel.
I know that in both cases $AB$ is rotated by the same angle but that is not enough for me to understand why they are parallel.
thanks.