Reasoning and Proof DAY 3: 2.3 Biconditional Statements.
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Transcript of Reasoning and Proof DAY 3: 2.3 Biconditional Statements.
Reasoning and ProofDAY 3: 2.3 Biconditional Statements
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If an animal has 4 legs, then it is a dog.
If an animal does not have 4 legs, then it is not a dog.
If an animal is not a dog, then it does not have 4 legs.
F
F
T
bi- conditional
iff↔
If three points are collinear, then they lie on the same line.Three points lie on the same line iff they are collinear.
If I am skiing, then I am downhill skiing.Counterexample: waterskiing
reversiblecounterexample
If two lines are perpendicular, then they intersect to form right angles.If two lines intersect to form right angles, then they are perpendicular.Two lines intersect are
perpendicular iff they intersect to form right angles.
Good definitions: conditional and converse are true.
TrueFalse. Whale.
False. Rectangle.
False. Straight Angle.
True
True
2.3 PRACTICEHomework: