Thursday, February 22, 2007
Geometry (Class 51)
Announcements
Quiz next Friday-- focuses on Chapter 8 Opener, Chapter 8 Lesson 1, Proof by Contradiction
Overview
In the last class we established what we mean by the word “similar” and saw that we would be convinced that two triangles are similar if we new that at least two angles were congruent or if we knew that we could enlarge all of the sides by the same scale factor.
In this lesson we extend these ideas and apply them to create similar triangles, to determine if two triangles are similar, and to solve for missing lengths of sides in two similar triangles.
Textbook Sections
§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
Determining if two triangles are similar.
When triangles are similar, you can match up sides so that the ratio of the lengths between the two triangles are the same.
Key Skills
Using a scale factor to enlarge or reduce a triangle
Writing proportions when given two similar triangles
Calculating a scale factor when given two similar triangles
Measurement
Working with equivalent fractions
Vocabulary
ratio
proportion
geometric mean
Handouts
No Handouts Posted
Assignment
Chapter 8 Lesson 1--Through Practice Problem 15.
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