Two angles Congruent If two angles are complementary to Complements the same angle (or to two congruent Complementary Theorem angles), then the two angles are 2-6-4 congruent. Congruent Common Collinear Segments Given collinear points A, B, C and D Theorem arranged as shown, if , then . Congruent 2-7-1 Vertical Angles Vertical Angles Theorem Vertical angles are congruent. Congruent 2-7-2 Congruent angles If two congruent angles are 2-7-3 supplementary, then each angle is a Supplementary right angle. Right angle Chapter 3 Properties, Postulates and Theorems Parallel and Perpendicular Lines Postulate or What it says Key Words Picture Theorem Name If 2 parallel lines are cut by a transversal, then… Parallel lines Corresponding angles …the corresponding Transversal Angles are congruent. Postulate Corresponding angles Parallel lines Alternate Transversal alternate interior angles …the Interior Angles are congruent. Alternate interior angles Theorem Alternate Parallel lines alternate exterior …the Exterior Angles
Congruent Complements Theorem 2-6-4 If two angles are complementary to the same angle (or to two congruent angles), then the two angles are congruent. Two angles Complementary Congruent Common Segments Theorem 2-7-1 Given collinear points A, B, C and D arranged as shown, if , then . Collinear Congruent Vertical Angles Theorem 2-7-2 Vertical angles are congruent. Vertical Angles Congruent 2-7-3 If two congruent angles are supplementary, then each angle is a right angle. Congruent angles Supplementary Right angle Chapter 3 Properties, Postulates and Theorems Parallel and Perpendicular Lines Postulate or Theorem Name What it says Key Words Picture If 2 parallel lines are cut by a transversal, then… Corresponding Angles Postulate …the corresponding angles are congruent. Parallel lines Transversal Corresponding angles Alternate Interior Angles Theorem …the alternate interior angles are congruent. Parallel lines Transversal Alternate interior angles Alternate Exterior Angles …the alternate exterior Parallel lines