Tuesday, January 13, 2009
Geometry (Class 42)
Announcements
Test Wed. 12/17 focusing on proving lines parallel.
Lesson Title
Constructions 3.7
Overview
The warm-up for the day asks students to figure out a way to construct a figure. The lesson for the day continues to focus on constructing triangles given using the lengths of three segments. As time permits we will begin to investigate constructing triangles using combinations of angles and sides.
Textbook Sections
§5.5 (txt. p.295) Inequalities in One Triangle
Vocabulary
construction
straight edge
arc
radius
center
diameter
Key Attitudes
Math is about being convinced a statement is always true.
Key Ideas
A straight edge and compass can be used to create geometric figures.
A compass is used to measuring lengths by making circles and arcs.
Some parts of a construction can be places wherever you want, while others have to be determined.
If you want a line to be in a specific location, then you have to have two points that it goes through. These points can be created by the intersection of two lines, two arcs, or a line and an arc.
It is not possible to construct a triangle out of just any three line segments!
Key Skills
I can construct a triangle from three line segments.
I can determine if it is possible to construct a triangle when given three line segments, or the lengths of three line segments.
I can determine the possible lengths for the third side of a triangle when given the lengths of two of the triangles sides.
I can determine if a triangle will be acute, right, or obtuse based on the lengths of the sides of the triangle.
I can determine the location of the smallest or the location of the largest angle when given the lengths of the sides of a triangle.
Turn-In (#41)
Finish Constructions 3.5
Handouts
Constructions 3.7
Geometry Key Concepts Fall 2008/2009
Geometry Key Skills Fall 2008/2009
Assignment
Constructions 3.7
Txt. p.175 #7-9, 13-16, 21, 22, 25, 26, 32, 33, 38, 39
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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