Two angles whose measures add to 90°.
Angles that have the same measure
Angles formed by two intersecting lines, and are opposite each other. They are also congruent.
Two angles whose measures add to 180°
A ray that divides a given angle into two congruent angles, each half the size of the given angle
A transformation that moves points the same distance and in the same direction
Lines that intersect to form right angles
Pairs of nonadjacent angles that lie on the same side of a transversal of two lines and in corresponding positions