Download 2-4 Deductive Reasoning

2-4 Deductive
Reasoning
Honors Geometry
Vocabulary
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
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Deductive Reasoning
Law of Detachment
Law of Syllogism
Law of Detachment

If p → q is TRUE and p is TRUE then
q is also TRUE
1.
CD teachers have an in-service on October 3rd.
Mr. Fields is a CD teacher.
Mr. Fields has an in-service on October 3rd.
2.
3.
Example
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Using Law of Detachment, come up with
conclusions for the following:
1.
The football team has a game on Friday.
Micah Parsons is a member of the football team.
2.
3.
1.
2.
3.
All cars have 4 wheels.
A Honda Accord is a car.
Example

Using Law of Detachment, come up with
conclusions for the following:
1.
The football team has a game on Friday.
Micah Parsons is a member of the football team.
Micah Parsons has a game on Friday.
2.
3.
1.
2.
3.
All cars have 4 wheels.
A Honda Accord is a car.
A Honda Accord has 4 wheels.
Law of Syllogism

If p → q and q → r is TRUE, then p → r is TRUE.
1.
If you wear a sleeveless shirt and violate the dress
code you will need to go to the office.
If you go to the office you will need to change your
clothes.
If you wear a sleeveless shirt and violate the dress
code you will need to change your clothes.
2.
3.
Law of Syllogism

If p → q and q → r is TRUE, then p → r is TRUE.
1.
If you wear a sleeveless shirt and violate the dress
code you will need to go to the office.
If you go to the office you will need to change your
clothes.
If you wear a sleeveless shirt and violate the dress
code you will need to change your clothes.
2.
3.
Ex last one:
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Using Law of Syllogism, come up with a
valid conclusion for the following:
1.
If you attend CDHS then your mascot is the ram.
If your mascot is the ram, then your colors are green and white.
2.
3.
1.
2.
3.
Perpendicular lines create right angles.
Right angles measure 90˚.
Ex last one:

Using Law of Syllogism, come up with a
valid conclusion for the following:
1.
If you attend CDHS then your mascot is the ram.
If your mascot is the ram, then your colors are green and white.
If you attend CDHS, then your colors are green and white.
2.
3.
1.
2.
3.
Perpendicular lines create right angles.
Right angles measure 90˚.
Perpendicular lines create angles that measure 90˚.