vertical angles, Vertical Angles are the angles opposite each other when two lines cross. "Vertical" in this case means they share the same Vertex (corner point), not the usual meaning of up-down.
Complementary angles are two angles with a sum of 90º. Supplementary angles are two angles with a sum of 180º. Vertical angles are two angles whose sides form two pairs of opposite rays. We can think of these as opposite angles formed by an X.
