Tuesday, February 20, 2007
Geometry (Class 50)
Overview
Today we begin our study of similarity by discussing what is required to be convinced that two triangles are the same shape, though not necessarily the same size. We then extend these ideas to include the concept of a scale factor, a number by which you can multiply all of the sides of a triangle to produce another triangle similar in shape to the first. We then investigate the implications of this enlargement.
In addition, we take our first quiz for the second semester.
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
If the angles of two triangles are equal, the triangles are similar.
If the sides of two triangles have the same scale factor, the triangles are similar.
If you multiply the sides of a triangle by the same amount and then use these measurements to construct a new triangle, the two triangles will be similar
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
Scale factor
ratio
proportion
Handouts
Chapter 8- Lesson 1
Assignment
Chapter 8 Lesson 1 #1-5
Txt. p.796 #1, 2, 9, 10
Txt. p.812 #18, 21, 23, 26, 29
Txt. p.811 #6
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