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Proving Lines Parallel

  • Postulates:
    • If two lines in a plane are cut by a transversal so that corresponding angles are congruent, then the lines are parallel
    • If two lines in a plane are cut by a transversal so that a pair of alternate exterior angles are congruent, then the two lines are parallel
    • Parallel Postulate: IF there is a line and a point not on the line, then there exists exactly one line through the point that is parallel to the given line
  • Theorems:
    • If two lines in a plane are cut by a transversal so that a pair of consecutive interior angles is supplementary, then the lines are parallel
    • If two lines in a plane are cut by a transversal so that a pair of alternate interior angles is congruent, then the lines are parallel
    • In a plane, if two lines are perpendicular to the same line, then they are parallel

Proving Lines Parallel

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Mathematics: Geometry