There is a connection between reflections, translations and rotations. 

Theorem 1:  When a figure is reflected in two parallel lines, the end result is the same as a translation in the direction perpendicular to the parallel lines and twice the distance between them.

For example, if triangle ABC is reflected in line l₁ and the image is reflected in line l₂, then the final image (triangle DEF) is a translation of triangle ABC through 6 units:

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