Wednesday, January 28, 2009
Geometry (Class 45)
Announcements
Test Wed. 12/17 focusing on proving lines parallel.
Lesson Title
Proving Triangles Congruent (1)
Overview
The opener for the class today is a construction puzzle requiring the ability to construct parallel lines and find the midpoints of segments. The lesson continues with the construction theme by practicing the construction of triangles given various pieces of a triangle: SSS, SAS, ASA, AAS, AAA, SSA. Some of these combinations result in a “fixed” triangle while other combinations allow the triangle to be altered while the initial conditions are still being met.
Textbook Sections
§4.3 (Txt. p.212) Proving Triangles Congruent
Vocabulary
construction
straight edge
arc
radius
center
diameter
adjacent
opposite
included
non-included
Key Attitudes
Math is about being convinced a statement is always true.
Key Ideas
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 parallel lines.
I can construct the midpoint of a segment.
I can construct a triangle given the lengths of its three sides (SSS).
I can construct a triangle given its three angles (AAA).
I can construct a triangle given two adjacent sides and an included angle (SAS).
I can construct a triangle given two angles and the included side (ASA)
I can construct a triangle given two angles and the non-included side (AAS).
I can construct a triangle given given two sides and a non-included angle (SSA).
Turn-In (#45)
§ (Txt. p.)
Handouts
No Handouts Posted
Assignment
Txt. p.298 #6-20
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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