2/15 Geometry Bell RingerGiven that DE // AB, find EB and AB.

Homework: Similarity Proofs Day 1 Independent Practice

2/15 News and Notes

• Perfection Award: 1st Period• HW Checked?• Quiz Make-ups and retakes today in 218• Need to serve a detention? Today in 218

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Perfection Competition Daily Results

Quiz Make-ups

• 1st: Brishanika, Kenneth, • 7th: Kaneisha, D’Antoinette, Selena, Tatyana,

Leslie• 8th: Cristian E, Angela, Coraima, Daniel, Lorena,

Brittany, Jasmine Z

Today’s Goal

• Use our Similarity Postulates to prove two triangles are similar.

• What were our 3 Similarity Postulates?

• SSS, SAS, and AA

• In order for two triangles to be similar, what must be true?

• 1. Corresponding angles congruent• 2. Corresponding sides proportional

Example 1• This example is just to get us comfortable with

the process of a proof.• Given: AC = 5, BE = 10,

CB = 3, DE = 6,

Prove: ∆ACB~ ∆BED

Step 1: Mark Given InformationStep 2: Check sides.

A B

C

D

E

EmCm

Example 2• Given:

Prove: ∆ACB~ ∆BED

Step 1: Mark Given InformationStep 2: Check sides.

A B

C

D

E

EmCm BDEmABCm

Guided Practice• Let’s take it up a notch - • Given: AC = BC = 6cm

EC = DC = 4cmProve: ∆ACB~ ∆ECD

Statement Reason

1. AC = BC = 6cm; EC = DC = 4 1. Given

2. DCEC

BCAC

2. Substitution

3. BCAmDCEm 3. Vertical Angles

4. ∆ACB~ ∆ECD 4. SAS

Independent Practice

• If you finish, here’s the bonus question: