21 Geometry Bell Ringer Of the three rectangles

2/1 Geometry Bell Ringer Of the three rectangles, which two are similar and why? 1 3 3 cm 4 cm 2 6 cm 18 cm 24 cm Homework: Proportions Worksheet 16 cm

2/1 News and Notes • HW Checked? • Absent Yesterday? Bathroom/Locker Passes • Perfection Award: 4 th Period – Great attitude during discovery activity.

Your 5 Rules • 1. Give Respect, Get Respect • 2. Be on time and start bell ringer right away • 3. Prepared means binder, homework, pen/pencil, and handouts for today are ready. • 4. “I Can” not “I Can’t” • 5. Quiet when others are talking

Consequences • 1. Warning • 2. Lost Points for the Day • 3. Lost Points for the Week & Phone call home • 4. Write-up • 5. Up to the office • ** Tardy twice in a week? Detention on Mon.

2/1 Agenda • • • I CAN set up and solve a proportion. 1. Bell Ringer 2. Algebra Examples 4. Guided Practice 5. Independent Practice 6. ACT Question of the Day

How to solve a proportion • Example: 3 x = 18(4) 3 x = 72 3 x/3 = 72/3 • “ 3 is to 4 as 18 is to x” • Once the proportion is set up: – Step 1: Cross Multiply – Step 2: Simplify X = 24

What’s a scale factor? • Scale factor: How much bigger or smaller. • Key words: – Multiplier – Magnitude – “x times as big” 18/3 = 6 = Scale Factor In words: “ 18 is 6 times larger than 3” Therefore, enlargement

All together? Solve for x, then find scale factor: 15 x = 30(3) 15 x = 90 15 15 x = 6. 3/15 = 1/5 = Scale Factor In words: “ 3 is 1/5 th of 15. ” Therefore, reduction!

Get Stamped before doing puzzle. • • Step 1: Step 2: Step 3: Step 4: Reduction or Enlargement? Solve for x What’s the scale factor? Check your scale factor 1: Enlargement (24 > 8) 2: 8 x = 3(24) 8 x/8 = 72/8 x =9 3: 24/8 = 3 1: Enlargement (5 > 2) 2: 2 x = 9(5) 2 x/2 = 45/2 x = 22. 5 3: 5/2 = 2. 5 or just 5/2 4: 9 x (5/2) = 22. 5 YES!!! 1: Reduction (4 < 14) 2: 14 x = 8(4) 14 x/14 = 32/14 x = 2. 29 3: 4/14 = 2/7 = 0. 286 4: 8 x (2/7) = 2. 29 YES

Independent Practice • FOR FULL CREDIT YOU MUST SHOW YOUR WORK ON A SEPARATE SHEET OF PAPER. • NO WORK = NO CREDIT!