∥
parallel lines
∠
angle
angles that add up to 180°
supplementary
two angles that share a common vertex and a common side (ray), but do not overlap
Adjacent angle
pairs of opposite, non-adjacent angles formed by two intersecting straight lines
Vertical angles
pairs of angles on opposite (alternate) sides of a transversal line and between (interior) two other lines.
Alternate interior angles
pairs of angles in matching corners formed when a transversal intersects two lines, located on the same side of the transversal and in the same relative position
corresponding angles