section 2-1: conditional statements goal: be able to recognize conditional statements, and to write...
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Section 2-1: Conditional StatementsGoal: Be able to recognize conditional statements, and
to write converses of conditional statements.
If you eat your vegetables, then you will grow up to be big and strong.
conditional statement: _________________________________________
an if-thenstatement
hypothesis: ____________________
conclusion: ____________________
follows the if part
follows the then part
If you eat your vegetables, then you will grow up to be big and strong.
Hypothesis: ______________________You eat your vegetables
Conclusion: ______________________________________________________
You will grow up to be bigand strong
If 2 lines are perpendicular, then they form a right angle.Hypothesis: ______________________
Conclusion: ______________________2 lines are perpendicularThey form a right angle
Writing Conditional Statements
Ex 1: An angle of 150° is obtuse._____________________________________If an angle is 150°, then it is obtuse.
Ex 2: A parallelogram has opposite sides parallel.
If a figure is a parallelogram, then it has __________________________________________________________________________opposite sides parallel.
A conditional can have a _____________ of true or false.
truth value
Find a counterexample where the hypothesis is _________ and the conclusion is _________.
truefalse
Ex 3: Odd integers less than 10 are prime.
Counterexample: _____________________9Ex 4: If I scored a goal, then I played soccer.Counterexample: _____________________hockey
(If an odd integer is less than 10, then it is prime.)
Use a Venn Diagram to illustrate the conditional statement.
Ex 4: If a food is a tomato, then it is a fruit.
tomato
fruit
converse: ________________________________________________________________
switches the hypothesis and conclusion of a conditional statement
Conditional: If two lines have the same slope, then the lines are parallel.Converse: _______________________________________________________________
Ex 5: Conditional: If 3 points are noncollinear, then they determine a plane.Converse: _______________________________________________________________
If 3 points determine a plane, then they are noncollinear.
If two lines are parallel, then they have the same slope.
inverse: ____________________________________________________________________________________________________
negates the hypothesis and negates the conclusion of a conditional statement contrapositive:____________________________________________________________
switches the hypothesis and conclusion and negates both of them Conditional: If two lines have the same slope, then the lines are parallel.inverse: _______________________________________________________________
If two lines do not have the same slope, then the lines are not parallel.
contrapositive: __________________________________________________________
If two lines are not parallel, then they do not have the same slope.
Finding the Truth Value of a Conditional and ConverseEx 6: Conditional: If 2 lines do not intersect, then they are parallel.
Converse: _______________________________________________________________
If 2 lines are parallel, then they do not intersect.
Conditional is : _______________________Converse is : _________________________
False (counterexample: skew) True
Ex 7: Conditional: If a figure is a square, then it has four right angles.
Converse: _______________________________________________________________
If a figure has four right angles, then it is a square.
Conditional is : _______________________
Converse is : _________________________
True
False (counterexample: rectangle)
SummaryIf a circle’s radius is 3 m, then its circumference is 6π m.
1.) Identify the hypothesis and conclusion.Hypothesis: ____________________________________Conclusion: ____________________________________
2.) Write the converse.____________________________________________________________________________________________
3.) Determine the truth value of the conditional and its converse.Conditional:____________________________________Converse: _____________________________________
A circle’s radius is 3 m Its circumference is 6 π m
If a circle’s circumference is 6 π m, then its radius is 3 m.
TrueTrue
4.) Show that the conditional is false by finding a counterexample.All numbers containing the digit 0 are divisible by 10.
(If a number contains the digit 0, then it is divisible by 10.)
Counterexample: _______________________________105