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Learn essential math properties of equality, definitions of congruence and midpoint, angle bisector theorems, and how to use them in proofs. Understand VAT, EST, SAT, CAT, and angle relationships.
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2.2 Proof Properties Memorize these ASAP!
Properties of Equality Addition Property of Equality: _________________________________ Subtraction Property of Equality: ________________________________ Multiplication Prop. of Equality: ________________________________
Division Property of Equality: ________________________________ Substitution Property of Equality: _______________________________ Reflexive Prop. of Equality: _______________________________ Symetric Prop. of Equality: _______________________________
Transitive Property of Equality: _________________________________ Definition of Congruence: ______________________________________________ ______________________________________________ ______________________________________________ ______________________________________________
Definition of a Midpoint: ______________________________________ Midpoint Theorem: ________________________________________________ ________________________________________________ ________________________________________________ A X B
Definition of Angle Bisector: ______________________________________ Angle Bisector Theorem: ______________________________________________ ______________________________________________ A Y B C
Vertal Angle Theorem (VAT): Segment Addition Postulate (SAP): Angle Addition Postulate (AAP): 1 2 A B C A D B C
Proof- ____________________________ __________________________________ We will now use all the theorems, postulates and properties we just defined to solve proofs. Lets try a Algebra Proof first.
Given: 4x+3 = 2x -9 Prove: x= -6 Given always first statement and reason! Statements Reasons
A B C D E F
A B C D
A B C D
Have we noticed a pattern? • Parts to Whole (given pieces, asked to prove whole) • ______________________________________ • ______________________________________ • ______________________________________ • Whole to Parts (given Whole, asked to prove parts) • ______________________________________ • ______________________________________ • ______________________________________
K G H J K
E F H G
A B C D E F
S Q P 3 4 1 2 R T
S Q P Z 3 4 1 2 R T
S Q P Z 3 4 1 2 R T
S Q P Z 3 4 1 2 R T
3 1 2
C B D 3 1 2 4 A E F
Lets Prove VAT 3 1 2
VAT- ___________________________ ________________________________________________________________________________________________ Supplement and Complement:
Complete with Always, Sometimes or Never • Vertical angles____________ have a common vertex? • 2 right angles are _________complementary. • Right angles are _________ vertical angles. • Vertical angles___________ have a common supplement.
Lets Prove VAT 1 2 3 4
Definition of Perpendicular Lines: • _____________________________________________________________________ • ________________________________________________________________________________________________________
Theorem 2-4:___________________________ ____________________________________________________________________________ s 1 2 t
Definition of Complementary Angles ________________________________________ ________________________________________ Definition of Supplementary Angles _________________________________________ _________________________________________ _________________________________________
Exterior Sides Theorem (EST): ___________________________________________________________________________________________________________________________ S 2 1 T ___________________________________________________________________________________________________________________________
E C A G • True or False: • Angle CGB is a right angle? • Angle CGA is a right angle? • Angle DGB is 90 degrees? • EGC and EGA are compliments? • DGF is complementary to DGA? • EGA is complementary to DGF B D F
Supplementary Angle Theorem (SAT) ________________________________________ ________________________________________ ________________________________________ ________________________________________ ________________________________________ Example: If 1 is supp to 2 and 2 is sup to 3 Then SAT says
Complementary Angle Theorem (CAT) ____________________________________________________________________________________________________________________________________________________________________________________ Example: If 1 is comp to 2 and 2 is comp to 3 Then CAT says
When to use? • ___________________________________________________________________________________ • ___________________________________________________________________________________ • ___________________________________________________________________________________ • ___________________________________________________________________________________
1 2 4 3
3 4 1 2
2 1 3 4
A 3 2 1 C B
1 2 3 4
1 2 3 4
1 2 3 4