Download PROPERTIES For any numbers a, b, c, and d: (Arithmetic) 1

PROPERTIES
For any numbers a, b, c, and d:
(Arithmetic)
1. Commutative Property: a + b = b + a
2. Commutative Property of Multiplication: ab = ba
3. Associative Property of Addition: (a + b) + c = a + ( b + c)
4. Associative Property of Multiplication: (ab)c = a(bc)
5. Distributive Property: a(b +c) = ab + ac
(Equality)
6. Reflexive Property: a = a (any number is equal to itself)
7. Transitive Property (or Substitution): If a = b and b = c, then a = c.
8. Symmetric Property: If a = b, then b = a.
9. Addition Property: If a = b, then a + c = b + c.
10. Subtraction Property: If a = b, then a – c = b – c.
11. Multiplication Property: If a = b, then ac = bc.
12. Division Property: If a = b, then
𝑎
𝑐
𝑏
= provided c≠0.
𝑐
13. Square Root Property: If 𝑎2 = 𝑏, 𝑡ℎ𝑒𝑛 𝑎 = ±√𝑏.
14. Zero Product Property: If ab = 0, then a = 0 or b = 0 or both a and b = 0.
15. Definition of Congruence: If AB = CD, then ABCD, and Conversely if ABCD, then AB = CD. Or if mA= mB, then
AB and conversely, if AB, then mA= mB.
POSTULATES
1. Line Postulate: You can construct exactly one line through any two points. In other words, two points determine a line.
2. Line Intersection Postulate: The intersection of two distinct lines is exactly one point.
3. Segment Duplication Postulate: You can construct a segment congruent to another segment.
4. Angle Duplication Postulate You can construct an angle congruent to another angle.
5. Midpoint Postulate: You can construct exactly one midpoint on any line segment.
6. Angle Bisector Postulate: You can construct exactly one angle bisector in any angle.
7. Parallel Postulate: Through a point not on a given line, you can construct exactly one line parallel to the given line.
8. Perpendicular Postulate: Through a point not on a given line, you can construct exactly one line perpendicular to the given line.
9. Segment Addition Postulate: If point B is on AC and between points A and C, then AB + BC = AC.
10. Angle Addition Postulate: If point D lies in the interior of ABC , then mABD + DBC = mABC .
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11. Linear Pair Postulate: If two angles are a linear pair, then they are supplementary.
12. Corresponding Angles Postulate, or CA Postulate: If two parallel lines are cut by a transversal, then the corresponding angles
are congruent. Conversely, if two lines are cut by a transversal forming congruent corresponding angles, then the lines are
parallel.
13. SSS Congruence Postulate: If the three sides of one triangle are congruent to three sides of another triangle, then the two
triangles are congruent.
14. SAS Congruence Postulate: If two sides and the included angle in one triangle are congruent to two sides and the included angle
in another triangle, then the two triangles are congruent.
15. ASA Congruence Postulate: If two angles and the included side in one triangle are congruent to two angles and the included side
in another triangle, then the two triangles are congruent.
PARALLEL LINES THEOREMS
1. Vertical Angles Theorem, or VA Theorem: If two angles are vertical angles, then they are congruent (have equal measures).
2. Alternate Interior Angles Theorem, or AIA Theorem: If two parallel lines are cut by a transversal, then the alternate interior
angles are congruent.
3. Congruent and Supplementary Theorem: If two angles are both congruent and supplementary, then each is a right angle.
4. Supplements of Congruent Angles Theorem: Supplements of congruent angles are congruent.
5. Right Angles Are Congruent Theorem: All right angles are congruent.
6. Converse of the AIA Theorem: If two lines are cut by a transversal forming congruent alternate interior angles, then the lines are
parallel.
7. Alternate Exterior Angles Theorem, or AEA Theorem: If two parallel lines are cut by a transversal, then the alternate exterior
angles are congruent.
8. Converse of the AEA Theorem: If two lines are cut by a transversal forming congruent alternate exterior angles, then the lines are
parallel.
9. Interior Supplements Theorem: If two parallel lines are cut by a transversal, then the interior angles on the same side of the
transversal are supplementary.
10. Converse of the Interior Supplements Theorem: If two lines are cut by a transversal forming interior angles on the same side of
the transversal that are supplementary, then the lines are parallel.
11. Parallel Transitivity Theorem: If two lines in the same plane are parallel to a third line, then they are parallel to each other.
12. Perpendicular to Parallel Theorem: If two lines in the same plane are perpendicular to a third line, then they are parallel to each
other.
TRIANGLE THEOREMS
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13. Triangle Sum Theorem: The sum of the measures of the angles of a triangle is 180°.
14. Third Angle Theorem: If two angles of one triangle are congruent to two angles of another triangle, then the third angle in each
triangle is congruent to the third angle in the other triangle.
15. SAA Congruence Theorem: If two angles and a non-included side of one triangle are congruent to the corresponding angles and
side of another triangle, then the triangles are congruent.
16. Angle Bisector Theorem: Any point on the bisector of an angle is equidistant from the sides of the angle.
17. Perpendicular Bisector Theorem: If a point is on the perpendicular bisector of a segment, then it is equally distant from the
endpoints of the segment.
18. Converse of the Perpendicular Bisector Theorem: If a point is equally distant from the endpoints of a segment, then it is on the
perpendicular bisector of the segment.
19. Converse of the Angle Bisector Theorem: If a point is equally distant from the sides of an angle, then it is on the bisector of the
angle.
20. Perpendicular Bisector Concurrency Theorem: The three perpendicular bisectors of a triangle are concurrent.
21. Angle Bisector Concurrency Theorem: The three angle bisectors of a triangle are concurrent.
22. Triangle Exterior Angle Theorem: The measure of an exterior angle of a triangle is equal to the sum of the measures of the
remote interior angles.
23. The Pythagorean Theorem: In a right triangle, the sum of the squares of the lengths of the legs equals the square of the length of
the hypotenuse. If a and b are the lengths of the legs, and c is the length of the hypotenuse, then a2 + b2 = c2.
24. Converse of the Pythagorean Theorem: If the lengths of the three sides of a triangle satisfy the Pythagorean equation, then the
triangle is a right triangle.
25. Hypotenuse Leg Theorem: If the hypotenuse and one leg of a right triangle are congruent to the hypotenuse and one leg of
another right triangle, then the two triangles are congruent.
26. Triangle Midsegment Theorem: A midsegment of a triangle is parallel to the third side and half the length of the third side.
(Isosceles Triangles)
27. Isosceles Triangle Theorem: If a triangle is isosceles, then its base angles are congruent.
28. Converse of the Isosceles Triangle Theorem: If two angles of a triangle are congruent, then the triangle is isosceles.
29. Medians to the Congruent Sides Theorem: In an isosceles triangle, the medians to the congruent sides are congruent.
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30. Angle Bisectors to the Congruent Sides Theorem: In an isosceles triangle, the angle bisectors to the congruent sides are
congruent.
31. Altitudes to the Congruent Sides Theorem: In an isosceles triangle, the altitudes to the congruent sides are congruent.
32. Isosceles Triangle Vertex Angle Theorem: In an isosceles triangle, the altitude to the base, the median to the base, and the
bisector of the vertex angle are all the same segment.
QUADRILATERAL THEOREMS
33. Quadrilateral Sum Theorem: The sum of the measures of the four angles of a quadrilaterals 360°.
34. Parallelogram Diagonal Lemma: A diagonal of a parallelogram divides the parallelogram into two congruent triangles.
35. Opposite Sides Theorem: The opposite sides of a parallelogram are congruent.
36. Opposite Angles Theorem: The opposite angles of a parallelogram are congruent.
37. Converse of the Opposite Sides Theorem: If the opposite sides of a quadrilateral are congruent, then the quadrilateral is a
parallelogram.
38. Converse of the Opposite Angles Theorem: If the opposite angles of a quadrilateral are congruent, then the quadrilateral is a
parallelogram.
39. Opposite Sides Parallel and Congruent Theorem: If one pair of opposite sides of a quadrilateral are parallel and congruent, then
the quadrilateral is a parallelogram.
40. Rhombus Angles Theorem: Each diagonal of a rhombus bisects two opposite angles.
41. Parallelogram Consecutive Angles Theorem: The consecutive angles of a parallelogram are supplementary.
42. Four Congruent Sides Rhombus Theorem: If a quadrilateral has four congruent sides, then it is a rhombus.
43. Four Congruent Angles Rectangle Theorem: If a quadrilateral has four congruent angles, then it is a rectangle.
44. Rectangle Diagonals Theorem: The diagonals of a rectangle are congruent.
45. Converse of the Rectangle Diagonals Theorem: If the diagonals of a parallelogram are congruent, then the parallelogram is a
rectangle.
46. Isosceles Trapezoid Theorem: The base angles of an isosceles trapezoid are congruent.
47. Isosceles Trapezoid Diagonals Theorem: The diagonals of an isosceles trapezoid are congruent.
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48. Converse of the Rhombus Angles Theorem: If a diagonal of a parallelogram bisects two opposite angles, than the parallelogram
is a rhombus.
49. Double-Edged Straightedge Theorem: If two parallel lines are intersected by a second pair of parallel lines that are the same
distance apart as the first pair, then the parallelogram formed is a rhombus.
50. Square Diagonals Theorem: The diagonals of a square are congruent, perpendicular, and bisect each other.
51. Converse of the Parallelogram Diagonals Theorem: If the diagonals of a quadrilateral bisect each other, then the quadrilateral is
a parallelogram.
52. Converse of the Kite Diagonal Bisector Theorem: If only one diagonal of a quadrilateral is the perpendicular bisector of the
other diagonal, then the quadrilateral is a kite.
53. Trapezoid Midsegment Theorem: The midsegment of a trapezoid is parallel to the bases and is equal in length to the average of
the bases.
54. Rectangle Midpoints Theorem: If the midpoints of the four sides of a rectangle are connected to form a quadrilateral, then the
quadrilateral formed is a rhombus.
55. Rhombus Midpoints Theorem: If the midpoints of the four sides of a rhombus are connected to form a quadrilateral, then the
quadrilateral formed is a rectangle.
56. Kite Midpoints Theorem: If the midpoints of the four sides of a kite are connected to form a quadrilateral, then the quadrilateral
formed is a rectangle.
CIRCLE THEOREMS
57. Tangent Theorem: A tangent to a circle is perpendicular to the radius drawn to the point of tangency.
58. Converse of the Tangent Theorem: A line that is perpendicular to a radius at its endpoint on the circle is tangent to the circle.
59. Perpendicular Bisector of a Chord Theorem: The perpendicular bisector of a chord passes through the center of the circle.
60. Arc Addition Postulate: If point B is on AC and between points A and C, then m AB + mBC = m AC .
61. Inscribed Angle Theorem: The measure of an angle inscribed in a circle equals half the measure of its intercepted arc.
62. Inscribed Angles Intercepting Arcs Theorem: Inscribed angles that intercept the same or congruent arcs are congruent.
63. Cyclic Quadrilateral Theorem: The opposite angles of a cyclic quadrilateral are supplementary.
64. Parallel Secants Congruent Arcs Theorem: Parallel lines intercept congruent arcs on a circle.
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65. Parallelogram Inscribed in a Circle Theorem: If a parallelogram is inscribed within a circle, then the parallelogram is a
rectangle.
66. Tangent Segments Theorem: Tangent segments from a point to a circle are congruent.
67. Intersecting Chords Theorem: The measure of an angle formed by two intersecting chords is half the sum of the measures of the
two intercepted arcs.
68. Intersecting Secants Theorem: The measure of an angle formed by two secants intersecting outside a circle is half the difference
of the measure of the larger intercepted arc and the measure of the smaller intercepted arc.
69. Product of Interior Segments Theorem: If two chords intersect in a circle, then the product of the segment lengths on one chord
is equal to the product of the segment lengths on the other chord.
SIMILIARITY THEOREMS
70. AA Similarity Postulate: If two angles of one triangle are congruent to two angles of another triangle, then the two triangles are
similar.
71. SAS Similarity Theorem: If two sides of one triangle are proportional to two sides of another triangle and the included angles are
congruent, then the triangles are similar.
72. SSS Similarity Theorem: If the three sides of one triangle are proportional to the three sides of another triangle, then the two
triangles are similar.
73. Corresponding Altitudes Theorem: If two triangles are similar, then corresponding altitudes are proportional to the
corresponding sides.
74. Corresponding Medians Theorem: If two triangles are similar, then corresponding medians are proportional to the
corresponding sides.
75. Corresponding Angle Bisectors Theorem: If two triangles are similar, then corresponding angle bisectors are proportional to the
corresponding sides.
76. Parallel/Proportionality Theorem: If a line passes through two sides of a triangle parallel to the third side, then it divides the two
sides proportionally.
77. Converse of the Parallel/Proportionality Theorem:
proportionally, then it is parallel to the third side.
If a line passes through two sides of a triangle dividing them
78. Three Similar Right Triangles Theorem: If you drop an altitude from the vertex of a right angle to its hypotenuse, then it
divides the right triangle into two right triangles that are similar to each other and to the original right triangle.
79. Altitude to the Hypotenuse Theorem: The length of the altitude to the hypotenuse of a right triangle is the geometric mean
between the length of the two segments on the hypotenuse.
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