Vertical angles are angles in opposite corners of intersecting lines. So vertical angles always share the same vertex, or corner point of the angle. They’re a special angle pair because their measures are always equal to one another, which means that vertical angles are congruent angles.

Read MoreIn this lesson we’ll look at the angles formed when a pair of parallel lines is crossed by another line, called a “transversal.” When transversals cross parallel lines, they form angles with special angle relationships.

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