Thursday, December 06, 2007
Geometry (Class 34)
Lesson Title
Indirect Proof 2
Overview
In today’s class we practice using proofs by contradiction. These proofs take the form of making an assumption, then showing that the negation of this assumption leads to an obviously false outcome. (Note: This obviously false outcome frequently is a contradiction of something from the “given”.)
Textbook Sections
§5.6 (Txt. p.302) Indirect Proof
Vocabulary
contradiction
assumption
negate, negation
syllogism
proof by contradiction
indirect proof
Key Attitudes
Math is about reasoning and justifying.
Key Ideas
A statement can be proved true by first assuming that it is false and then showing that this leads to an impossible result.
Key Skills
Proving a statement is true by contradiction.
Writing the negation of a statement.
Using the proof by contradiction format to write a proof by contradiction.
Turn-In (#33)
§4.7 (Txt. p.247) #6-19
§4.6 (Txt. p.239) #10, 14-16, 19, 22, 23
Handouts
No Handouts Posted
Assignment
Finish Chapter 4- Lesson 6
Txt. p. 255 (Chapter Test) #1-10, 15, 18
Disclaimer- The assignment as stated in class is the official assignment. Every effort is made to keep this posting accurate, but you should refer to what was stated in class as the final word.
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