cond, bicond, ded and algebra
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Transcript cond, bicond, ded and algebra
Conditionals, Biconditionals, and Deductive
Reasoning and algebraic properties
Be able to write a converse of a conditional
statement (Geometry and Spatial Sense, GR9,1)
Be able to write a biconditional
(Geometry and Spatial Sense, GR9,1)
Use law of detachment and law of
syllogism to draw conclusions
(Geometry and Spatial Sense, GR9,1)
Use algebraic properties to prove a
statement (Geometry and spatial sense, GR9, 1)
Lets begin with an OGT question….
The graph as shown represents the amount of money Sarah can earn at
her part-time job
Which of the following equations best represents the relationship
between Sarah’s pay and the hours she works?
A. y = 4x
B. y = 6.5x
C. y = 4x + 10
D. y = 6.5x + 10
If-Then Statements
Hypothesis – If statement
Conclusion – Then statement
Identify the Hypothesis and Conclusion:
◦ If two lines are parallel, then they are coplanar
Identify the Hypothesis and Conclusion:
◦ If two lines are parallel, then they are coplanar
◦ Hypothesis: Two lines are parallel
◦ Conclusion: They are coplanar
Write the statement as a conditional
◦ An acute angle measures less than 90º
Identify the Hypothesis and Conclusion:
◦ If two lines are parallel, then they are coplanar
◦ Hypothesis: Two lines are parallel
◦ Conclusion: They are coplanar
Write the statement as a conditional
◦ An acute angle measures less than 90º
◦ If an angle is acute, then it measures less than 90
Converse
The converse
converse of
of aaconditional
conditional statement
if
• The
statement is
formed by exchanging the hypothesis and the
formed
by in
switching
the hypothesis and the
conclusion
the conditional.
conclusion
Example
3: in the conditional.
◦ Conditional- If a figure is a triangle, then it has three
– angles.
Conditional- If a figure is a triangle, then it has
three angles.
◦ Converse- If a figure has three angles, then it is a
triangle.
– Converse- If a figure has three angles, then it is a
triangle.
If x = 5, then x + 15 = 20
◦ Write the converse:
If x = 5, then x + 15 = 20
◦ Write the converse:
◦ If x + 15 = 20, then x = 5
◦ Write the Biconditional:
If x = 5, then x + 15 = 20
◦ Write the converse:
◦ If x + 15 = 20, then x = 5
◦ Write the Biconditional:
◦ X = 5 if and only if x + 15 = 20
Write two statements that form this
biconditional:
◦ Lines are skew if and only if they are noncoplanar
Write two statements that form this
biconditional:
◦ Lines are skew if and only if they are noncoplanar
◦ If lines are skew, then they are noncoplanar
◦ If lines are noncoplanar, then they are skew
If a conditional is true and its hypothesis is
true – then its conclusion is true
If p implies q is true and p is true then q is
true
Can you make a conclusion?…
◦ Every High School student likes music.
◦ Ling likes music
If a conditional is true and its hypothesis is
true – then its conclusion is true
If p implies q is true and p is true then q is
true
Can you make a conclusion?…
◦ Every High School student likes music. Ling likes
music
◦ If you are a high school student, then you like
music
If p implies q is true and q implies r is true,
then p implies r is true
P Q and QR, then PR
If a quadrilateral is a square, then it contains
4 right angles.
If a quadrilateral contains 4 right angles, then
it is a rectangle
A gardener knows that if it rains, the garden
will be watered.
It is raining.
If you want to build a skyscraper, start with a
good foundation. The foundation is a
concrete form that supports the rest of the
structure.
The foundation of geometry is made of
statements called postulates. These are
accepted as true.
Addition Property
Subtraction Property
Multiplication Property
Division Property
Reflexive Property
Symmetric Property
Transitive Property
Substitution Property
Distributive Property
Fill in…
3x
2x + 1
AB + BC = AC
3x + 2x + 1 = 36
5x + 1 = 36
5x = 35
X=
Simplify
AC = 36
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