What is a definition of a reflection of a preimage point p across line m? if a point p is on line m, then m is the perpendicular bisector of pp′, where p′ is the image of p. if p is not on line m, then p = p′. if a point p is on line m, then p = p′ where p′ is the image of p. if p is not on line m, then m is the bisector of pp′. if a point p is on line m, then p = p′, where p′ is the image of p. if p is not on line m, then pp′ is perpendicular to m. if a point p is on line m, then p = p′, where p′ is the image of p. if p is not on line m, then m is the perpendicular bisector of pp′.