Footprints

Investige combinations of two reflections in parallel and in intersecting mirror lines.

Suppose you have an infinite frieze pattern of footsteps. Investigate a combination of reflections that will give a glide reflection mapping any footstep in the pattern to the next one. Where would the mirror lines have to be? Show that, with the mirror lines you have chosen, the third step maps to the fourth, the fourth to the fifth and so on...