1. Pythagorean Theorem Theorem

2. a² + b² = c² a b c p. 20

3. Distance Formula Theorem

4. p. 19

5. Segment Addition Postulate Postulate

6. If B is between A and C, then AB + BC = AC. A B C  p. 18

7. Angle Addition Postulate Postulate

8. If P is in the interior of  ABC, then m  ABP + m  PBC = m  ABC A B C  p. 27   P

9. midpoint Definition

10. The midpoint is a point that divides or bisects a segment into two equal segments. If M is a midpoint, then AM = MC. A M C  p. 34

11. segment bisector Definition

12. A segment bisector is a line, ray, segment or plane that intersects a segment at its midpoint. A M C p. 34 k 

13. angle bisector Definition

14. An angle bisector is a ray that divides an angle into two congruent adjacent angles. 1 p. 36 2  1   2

15. Midpoint Formula Theorem

16. p. 35  M

17. complementary angles Definition

18. A pair of angles whose sum is 90° are complementary. 1 p. 46 2 m  1 + m  2 = 90

19. supplementary angles Definition

20. A pair of angles whose sum is 180° are supplementary. 1 p. 46 2 m  1 + m  2 = 180

21. right angle Definition

22. An angle whose measure is 90° is a right angle. p. 28 90°

23. perpendicular lines Definition

24. Two lines are called perpendicular if they intersect to form a right angle. p. 79

25. Reflexive Property

26. For any real number, a = a. p. 96 A B C D

27. Transitive Property

28. If a = b and b = c, then a = c. p. 96 A B.. C D.. E F.. If AB = CD and CD = EF, then AB = EF.

29. Addition Property of Equality Property

30. If a = b, then a + c = b + c. p. 96 A B C D... If AB = CD, then AC = BD..

31. Subtraction Property of Equality Property

32. If a = b, then a  c = b  c. p. 96 A B C D... If AC = BD, then AB = CD..

33. Substitution Property

34. If a = b, then a can be substituted for b in any equation or expression. p. 96 Example: If AB = 5 + x and x = 3, then AB = 8.

35. Right Angle Congruence Theorem Theorem

36. All right angles are congruent. 1 p. 110 2  1   2

37. Congruent Supplements Theorem Theorem

38. Two angles supplementary to the same angle (or   ’s) are congruent. 1 p. 111 2 3 If m  1 + m  2 = 180 and m  2 + m  3 = 180, then  1   3.

39. Congruent Complements Theorem Theorem

40. Two angles complementary to the same angle (or   ’s) are congruent. 1 p. 111 2 3 If m  1 + m  2 = 90 and m  2 + m  3 = 90, then  1   3.

41. Linear Pair Postulate Postulate

42. If two angles form a linear pair, then they are supplementary. p. 111 1 2 m  1 + m  2 = 180

43. Vertical Angles Theorem Theorem

44. Vertical angles are congruent. 1 2 p. 112  1   2 and  3   4 3 4

45. Linear Pair of   s Theorem

46. If two lines intersect to form a linear pair of congruent angles, then the lines are perpendicular. p. 137 g h g h

47. Corresponding Angles Postulate Postulate

48. If two parallel lines are cut by a transversal, then corresponding  ’s are . p. 143 1 1  2 1  2 2

49. Alternate Interior Angles Theorem Theorem

50. p. 143 If two parallel lines are cut by a transversal, then alt. int.  ’s are . 1 1  2 1  2 2

51. Alternate Exterior Angles Theorem Theorem

52. p. 143 If two parallel lines are cut by a transversal, then alt. ext.  ’s are . 1 1  2 1  2 2

53. Consecutive Interior Angles Theorem Theorem

54. p. 143 If two parallel lines are cut by a transversal, then consecutive int.  ’s are supplementary. 1 2 m  1 + m  2 = 180

55. Perpendicular Transversal Theorem Theorem

56. p. 143 If a transversal is perpendicular to one of two parallel lines, then it is perpendicular to the other. k j  m j m

57. Two Lines Perpendicular to Same Line Theorem

58. p. 157 In a plane, two lines perpendicular to the same line are parallel to each other. k j // m j m

59. Two Lines Parallel to the Same Line Theorem

60. p. 157 If two lines are parallel to the same line, then they are parallel to each other. k m // n n m

61. Triangle Sum Theorem Theorem

62. p. 196 The sum of the measures of the interior angles of a triangle is 180°. A B C m  A + m  B + m  C = 180

63. Exterior Angle Theorem Theorem

64. p. 197 The measure of an exterior angle of a triangle is equal to the sum of the two remote interior angles. A B 1 m  1 = m  A + m  B

65. Third Angles Theorem Theorem

66. p. 203 If two angles of one  are  to two angles of another , the third angles are . A B C D E F If  A   D and  B   E, then  C   F

67. SSS Side-Side-Side Congruence Postulate

68. p. 212 If three sides of one  are  to three sides of another , then the  ’s are . A B C D E F If,, and, then  ABC   DEF.

69. SAS Side-Angle-Side Congruence Postulate

70. p. 213 If two sides of one  are  to two sides of another , and the included  s are , then the  ’s are . A B C D E F If, and  A   D, then  ABC   DEF.

71. Perpendicular/Right  Theorem (Meyers Theorem) Theorem

72. p. 157 Perpendicular lines form  right  s. k j m If j  k and m  k, then  1   2. 1 2

73. ASA Angle-Side-Angle Congruence Postulate

74. p. 220 If two  s of one  are  to two  s of another , and the included sides are , then the  ’s are . A B C D E F If  A   D,  C   F and, then  ABC   DEF.

75. AAS Angle-Angle-Side Congruence Postulate

76. p. 220 If two  s of one  and a non-included side are  to two  s of another  and the corresponding non-included side, then the  ’s are . A B C D E F If  A   D,  C   F and, then  ABC   DEF.

77. Base Angles Theorem Theorem

78. p. 236 If two sides of a  are , then the  s opposite those sides are .

79. Base Angles Converse Theorem Theorem

80. p. 236 If two  s of a  are , then the sides opposite those  s are .

81. Hypotenuse-Leg Theorem H-L Theorem

82. p. 238 If the hypotenuse and a leg of one right  are  to a hyp. and a leg of another rt. , the two  s are . A B C D E F

83. Perpendicular Bisector Theorem Theorem

84. p. 265 If a point is on the  bisector of a segment, then it is equidistant from the endpoints of that segment. A B C k P AC = BC

85. Angle Bisector Theorem Theorem

86. p. 266 If a point is on the bisector of an angle, then it is equidistant from the sides of the angle. A B C P AP = CP

87. Circumcenter Theorem

88. p. 273 The perpendicular bisectors of a triangle intersect in a point that is equidistant from the vertices of the triangle.

89. Incenter Theorem

90. p. 274 The angle bisectors of a triangle intersect in a point that is equidistant from the sides of the triangle.

91. Centroid Theorem

92. p. 279 The medians of a triangle ( E, D, and F are midpoints) intersect in a point called a centroid. AP = 2 / 3 AD, BP = 2 / 3 BF, CP = 2 / 3 CE A F C E D B P

93. Orthocenter Theorem

94. p. 281 The altitudes of a triangle intersect in a point of concurrency called an orthocenter.