WARNING: Antidepressant medications are used to treat a variety of conditions, including depression and other mental/mood disorders. These medications can help prevent suicidal thoughts /attempts and provide other important benefits.
Definition of parallel for Students. 1  1 : a line or surface that lies at or moves in the same direction as another but is always the same distance from it. 2  2 : one of the imaginary circles on the earth's surface running in the same direction as the equator and marking latitude.
Two lines are parallel if and only if the two angles of any pair of corresponding angles of any transversal are congruent (equal in measure). Note: This follows directly from Euclid's parallel postulate. Further, if the angles of one pair are congruent, then the angles of each of the other pairs are also congruent.