Answer:△DEF is congruent to △D′E′F′ because the rules represent a translation followed by a reflection, which is a sequence of rigid motions.
Step-by-step explanation:
A rigid motion of the plane is a motion which maintain distance.
Translation is a kind of rigid motion used in geometry to trace a function that moves an object a particular distance.
A reflection is also a kind of rigid motion . It is mainly a 'toss' of a shape across the line of reflection.
So,△DEF is mapped to △D′E′F′ using the rule (x,y)→(x,y+1) ( which is a translation.) followed by (x,y)→(x,−y)(which is reflection),therefore it is a sequence of rigid motions.
