2.3 Homework Answers

10.) Inductive Reasoning12.) Valid

16.) Invalid    18.) Invalid

20.) A; Complementary angles are not necessarily adjacent so
they may not form a right angle.

26.) Either Andre is less than 35 years old, or he is not a
natural-born citizen. Among the possible answers: Since there
are 3 criteria to be eligible and he meets 1, he must not meet 1
of the remaining 2.




                                                                   1
2.4 Homework Answers

12.) Conditional: If a lunar eclipse occurs, then Earth is
between the Sun and the Moon.          Converse: If Earth is
between the Sun and the Moon, then a lunar eclipse occurs.

16.) False; possible answer: Felipe could be a swimmer

22.)no; possible answer: y = -8




                                                               2
2.5 Homework Answers

8.) Statements         Reasons
    1. C = 9f + 90     Given
    2. 102 = 9f + 90   Substitution
    3. 12= 9f          Subtraction Property of Equality
    4. f = 4/3         Division Property of Equality.

10.) Definition of congruent segments; Substitution;
Subtraction Property of Equality; Subtraction Property of
Equality; Division Property of Equality

12.) Reflexive Property of Congruence

14.) Symmetric Property of Equality

50.) Inductive Reasoning




                                                            3
Opener:

Have you ever wanted something so bad that you had to fight
for it? (NOT literally!) Maybe it was an allowance raise, a
car, your own room, or a later curfew? What types of
justifications did you use or say? Write down what you were
arguing/debating for and how you tried to PROVE you were
right.




                                                              4
2.6 Proof Strategy:

     Start with the hypothesis of the conditional, given          Hypothesis or 
                                                                     Given
     information, or information in the diagram.
           *Draw a picture or mark information
                 on a diagram already given.
                                                                Deductive Reasoning
     Apply deductive reasoning.                               *Definitions *Properties
                                                              *Postulates *Theorems




                                                                    Conclusion
     Prove that the conclusion of the conditional is true.




*Always be thinking about how you can get the conclusion to happen...
 what makes the conclusion true?




                                                                                         5
Given: L1 and L2 form a linear pair
     Prove: L1 and L2 are supplementary

                Statements                          Reasons
_______________________________________________________________________________




                                                                                  6
Given: L1 and L2 are supplementary
            L2 and L3 are supplementary
     Prove: L1 ≅ L3

                Statements                          Reasons
_______________________________________________________________________________




                                                                                  7
Given: LA and LB are right angles
 Prove: LA ≅ LB


          Statements                          Reasons
____________________________________________________________________________




                                                                               8
Given: L1 and L2 are complementary
       L2 and L3 are complementary
Prove: L1 ≅ L3
          Statements                          Reasons
____________________________________________________________________________




                                                                               9
Reference Sheet for Proofs: 

Get out a clean sheet of paper.  Label one side Definitions and the 
other side Theorems.




                                                                       10
Proof Writing 101:

    1. Start with 2 columns, labeled Statements & Reasons

    2. Number your statements and reasons so that they match
         *Reason #1 has information about Statement #1
         *Reason #3 explains how to move from statement #2 to #3

    3. Do NOT make your proofs look like the book's proofs
         *Properties identified by name
         *Definitions written as "If..., then..." sentences
         *Theorems written as "If..., then..." sentences

    4. Abbreviate when you can




                                                                   11
Partner Practice... Work with your partner on the following (this is your 
homework!)

              Pg. 113 #4‐6, 8, 9, 17‐23 odd, 28, 30




                                                                             12
Exit Slip

Work with you partner to complete and turn
in Pg. 103 # 1- 18 Even. When you are
finished you can begin your homework.




                                             13

2.3 Homework Answers

  • 1.
    2.3 Homework Answers 10.)Inductive Reasoning12.) Valid 16.) Invalid 18.) Invalid 20.) A; Complementary angles are not necessarily adjacent so they may not form a right angle. 26.) Either Andre is less than 35 years old, or he is not a natural-born citizen. Among the possible answers: Since there are 3 criteria to be eligible and he meets 1, he must not meet 1 of the remaining 2. 1
  • 2.
    2.4 Homework Answers 12.)Conditional: If a lunar eclipse occurs, then Earth is between the Sun and the Moon. Converse: If Earth is between the Sun and the Moon, then a lunar eclipse occurs. 16.) False; possible answer: Felipe could be a swimmer 22.)no; possible answer: y = -8 2
  • 3.
    2.5 Homework Answers 8.)Statements Reasons 1. C = 9f + 90 Given 2. 102 = 9f + 90 Substitution 3. 12= 9f Subtraction Property of Equality 4. f = 4/3 Division Property of Equality. 10.) Definition of congruent segments; Substitution; Subtraction Property of Equality; Subtraction Property of Equality; Division Property of Equality 12.) Reflexive Property of Congruence 14.) Symmetric Property of Equality 50.) Inductive Reasoning 3
  • 4.
    Opener: Have you everwanted something so bad that you had to fight for it? (NOT literally!) Maybe it was an allowance raise, a car, your own room, or a later curfew? What types of justifications did you use or say? Write down what you were arguing/debating for and how you tried to PROVE you were right. 4
  • 5.
    2.6 Proof Strategy: Start with the hypothesis of the conditional, given Hypothesis or  Given information, or information in the diagram. *Draw a picture or mark information on a diagram already given. Deductive Reasoning Apply deductive reasoning. *Definitions *Properties *Postulates *Theorems Conclusion Prove that the conclusion of the conditional is true. *Always be thinking about how you can get the conclusion to happen... what makes the conclusion true? 5
  • 6.
    Given: L1 andL2 form a linear pair Prove: L1 and L2 are supplementary Statements Reasons _______________________________________________________________________________ 6
  • 7.
    Given: L1 andL2 are supplementary L2 and L3 are supplementary Prove: L1 ≅ L3 Statements Reasons _______________________________________________________________________________ 7
  • 8.
    Given: LA andLB are right angles Prove: LA ≅ LB Statements Reasons ____________________________________________________________________________ 8
  • 9.
    Given: L1 andL2 are complementary L2 and L3 are complementary Prove: L1 ≅ L3 Statements Reasons ____________________________________________________________________________ 9
  • 10.
  • 11.
    Proof Writing 101: 1. Start with 2 columns, labeled Statements & Reasons 2. Number your statements and reasons so that they match *Reason #1 has information about Statement #1 *Reason #3 explains how to move from statement #2 to #3 3. Do NOT make your proofs look like the book's proofs *Properties identified by name *Definitions written as "If..., then..." sentences *Theorems written as "If..., then..." sentences 4. Abbreviate when you can 11
  • 12.
  • 13.
    Exit Slip Work withyou partner to complete and turn in Pg. 103 # 1- 18 Even. When you are finished you can begin your homework. 13