The three pictures show a pre-image, a middle image, and then a final image.[br][br]What happened first? How can you tell? Could it go the other way?[br][br]What changes as you drag point A?[br][br]What changes as you drag point D?[br][br]This is called a glide-reflection: A glide reflection is the composition of a translation (a glide) and a reflection across a line parallel to the direction of translation.