Remember a glide reflection *g* involve the combination of a reflection in
a mirror with a translation parallel to that mirror. But then the composition
of *g* with itself (*g*^{2}) will be a translation. By the above though,
the translation distance must be a *whole* number of units ....

**Mirrors:**- Where can this mirror be if the strip is to be transformed to itself?
**Translation Part:**- How many units can the translation part of the glide reflection be?