Thursday, January 15, 2009
Geometry (Class 43)
Announcements
Test Wed. 12/17 focusing on proving lines parallel.
Lesson Title
Constructions 4
Overview
The warm-up for the day is the second construction puzzle. Our lesson focuses on using angles and segments to construct triangles.
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.
Triangles can be constructed out of various combinations of angles and sides.
Only some combinations of angles and sides guarantee that all triangle created with this combination will be congruent-- the same size and the same shape. Other combinations only guarantee triangles which are the same shape, and some combinations guarantee nothing at all!
Key Skills
I can construct a triangle given a side and the two adjacent angles (ASA).
I can construct a triangle given two sides and the included angle (SAS).
I can copy a triangle.
I can construct a triangle given two sides and the non-included angle (SSA)
Turn-In (#42)
Constructions 3.7
Txt. p.175 #7-9, 13-16, 21, 22, 25, 26, 32, 33, 38, 39
Handouts
Constructions 4
Assignment
Constructions 4
Txt. p.175 #7-9, 13-16, 21, 22, 25, 26, 32, 33, 38, 39 (For B3 and B4 Only)
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.
Permalink