2/8 Geometry Bell Ringer - Mr. Chrischilles's Class

```2/8 Geometry Bell Ringer
1. Mr. Chrischilles made chili for his Super
Bowl Party. The recipe called for 2 cans
of chili beans in order to serve 5 people.
If Mr. Chrischilles needed to serve 20
people? (Set up proportion to solve)
2. What were the 4 Congruent Triangle
Postulates (shortcuts) that we used to
prove triangles were congruent?
Homework: Identifying Similar Triangles Indep. Practice
2/8 News and Notes
•
•
•
•
Perfection Award: 1st Period
HW Checked?
Tardy Policy Reminder
Remember, Quiz Friday!
Perfection Competition Daily Results
2
2
1.5
1
1
1
0.5
0
1st
2nd
4th
0
0
7th
8th
Today = A College Test
• Today is going to be different.
• Quick story about Prof. Chamlee-Wright
• 1. We will have a discussion for 10-15 minutes I will
pose questions, you will offer your thoughts.
• 2. Eventually you won’t need to raise your hands, but
today you will as we adapt.
• 3. Constructive Criticism: “I disagree, it seems to me
that
is true.”
• 4. EVERY COMMENT is VALUABLE
• 5. Today I’ll write important stuff on board, eventually I
won’t need to do this. You’ll write in your notes and
you’ll be able to use your notes on the 2 question quiz
after class.
Remember our new rules:
• 1. Give Respect, Get Respect –
Constructive Criticism
• 2. Be on time and start bell ringer right
away
• 3. Prepared means binder, homework,
pen/pencil, and handouts for today are
• 4. “I Can” not “I Can’t”
• 5. Quiet when others are talking
Questions driving conversation:
• From the bell ringer, what were our 4
postulates/shortcuts from Congruent Triangles?
• What’s the difference between congruent
triangles and similar triangles?
• Are congruent triangles still similar?
• What’d we say about AAA for congruent
triangles?
• Do we have to show all 3 angles, or can we
make similarity conclusion with fewer, why?
• AA Similarity Postulate:
• What is then guaranteed to be true about sides?
More Questions
• So we’ve used the angle portion of our
definition, what’s the other part of the
definition of similar triangles?
• If you knew that the three sides were
proportional, what would be true about the
angles? Why?
• SSS Postulate:
• Example.
More
• What other congruent triangle postulates
were there besides SSS?
• Why do we not need to talk about SAA or
ASA?
• SAS Postulate Example
• SSA still doesn’t work, why?
One Example, One Non-Example
1. Shortcut
SAS
2. Does it work to prove?
YES
3. Do proportions work?
2 6
 ?
4 12
24 = 24
One Example, One Non-Example
1. Shortcut
SSS
2. Does it work to prove?
YES
3. Do proportions work?
2 3
 ?
6 3
6 = 18
Independent Practice
• 5 examples, one non-example
• 3 steps:
– 1. Identify shortcut  Put in box
– 2. Check proportions if sides involved
– 3. If similar, state similar triangles.
2 Question Quiz
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