Question: A glide reflection is a composition of a \text{translation} followed by a \text{reflection}. As shown earlier, each of these can be expressed as a composition of reflections. It follows that their composition, a glide reflection, can also be expressed as a composition of reflections. Each type of rigid motion has now been considered, so the proof is complete.
1. \textbf{State the problem:} We want to understand what a glide reflection is and how it can be expressed as a composition of reflections.
2. \textbf{Definition:} A glide reflection is a rigid motion consisting of a \textbf{translation} followed by a \textbf{reflection}.
3. \textbf{Key fact:} Both translations and reflections can be expressed as compositions of reflections.
4. \textbf{Translation as reflections:} A translation can be represented as the composition of two reflections across parallel lines.
5. \textbf{Reflection:} A reflection is itself a single reflection.
6. \textbf{Composition:} Since a glide reflection is a translation followed by a reflection, it can be expressed as the composition of three reflections (two for the translation and one for the reflection).
7. \textbf{Conclusion:} Therefore, a glide reflection can be expressed as a composition of reflections, completing the proof that all rigid motions can be represented this way.