KL and MN are parallel lines. O is the midpoint of segment LM. Which transformation of the plane can we use to prove angles u and v are congruent, and why? a) A reflection over a line through O that is parallel to KL and MN maps ray LK onto MN and vice versa, and the same for rays LO and MO on top. This means angle u will be mapped onto angle v and vice versa.

b) A translation along the directed line segment ML maps line MN onto line KL and angle v onto angle u.

c) A 180 degree rotation about O maps ray LK onto MN and vice versa, and the same for rays LO and MO. This means angle u will be mapped onto angle v and vice versa.