Thursday, February 08, 2007
Geometry (Class 47)
Announcements
Quiz-- Next Thursday focusing on areas of quadrilaterals, proof by contradiction, and Chapter 8-Lesson 1
Overview
We continue our work learning how to use proof by contradiction (indirect proof). We also begin our work concerning similarity.
Textbook Sections
§5.6 (Txt. p.302) Indirect Proof
§8.1 (Txt. p.457) Ratio and Proportion
§8.2 (Txt. p.465) Problem Solving IN Geometry with Proportions
§8.4 (Txt. p.480) Similar Triangles
Key Attitudes
Mathematics is about justification.
Key Ideas
Some statements only have two possibilities-- either they are true or they are false.
If a statement can only be either true or false, then if you show that the statement is false, its opposite (negation) must be true.
If two figures are the same shape, then their corresponding sides are proportional-- in the same ratio-- and their corresponding angles are equal.
Key Skills
Proving statements using a proof by contradiction-- knowing the format of these proofs is critical.
Measurement
Working with equivalent fractions
Vocabulary
ratio
proportion
similar shapes
similarity
Handouts
No Handouts Posted
Assignment
Proof by Contradiction: Practice 1-4 (Will be collected)
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