Thursday, February 19, 2009
Geometry (Class 52)
Lesson Title
Proving Triangles Congruent (7)
Overview
The class begins with where we left off last class-- creating problems involving the identification of the correct triangle congruence postulate or theorem to use to prove triangles congruent. Students will then take a short quiz focusing on these skills. Afterwards. depending on the class, we will either investigate when, if ever, SSA can be used to prove two triangles congruent or we will move on to extend our proofs so that we can use congruent triangles as a step to further ideas.
Textbook Sections
§4.4 (Txt. p. 220) Proving Triangles Congruent
Vocabulary
construction
straight edge
arc
radius
center
diameter
adjacent
opposite
included
non-included
SSS
ASA
SAS
AAS
HL
Key Attitudes
Math is about building up understanding one idea at a time.
Key Ideas
A factor answers the question “How many of these are in this”?
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!
When multiplying two expressions, if the bases are the same the exponents need to be added.
Key Skills
I can identify key angle and side combinations which force triangles to be congruent.
I can identify and sequence the reasons which establish triangle congruence.
I can construct parallel lines.
I can construct the midpoint of a segment.
Turn-In (#51)
Finish Test 9 Follow-Up
Handouts
Chapter 4- Lesson 4: Proving Triangles Congruent
Assignment
Test 9 Corrections
Txt. p.239 #8-19, 33
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