1. 2.1 Patterns and Inductive Reasoning Geometry Chapter 2: Reasoning and Proof

2. How do you know? 1.Take a piece of paper. 2.Fold it in half then unfold it…How many rectangles do you have? 3.Refold the paper and fold it again. Unfold all the way…How many do you have now? 4.If you folded the paper in half 8 times…How many rectangles would you have?

3. Inductive Reasoning Reasoning based on patterns you OBSERVE Used in science - Conclusions made by using the scientific method

4. Finding and Using Patterns What are the next two terms in each sequence and what is the pattern description? 3, 9, 27, 81, … 45, 40, 35, 30,…

5. What are the next 2 terms? Finding and Using Patterns

6. Use Your Brain In order to figure out the nth-term in a sequence, we make a logical conclusion. Conjecture is a conclusion reached using inductive reasoning.

7. Using Inductive Reasoning What conjecture can you make about the number of regions after 20 diameters are drawn?

8. Make a Conjecture! R, W, B, R, W, B, R, W, B, … What will the 21 st term be?

9. Collect and Decide! What conjecture can you make about the sum of the first 30 even numbers? # of TermsSum 12= 2 = 1*2 22 + 4= 6 = 2*3 32 + 4 + 6= 12 =3*4 4 2 + 4 + 6 + 8= 20 = 4*5 What about the first 30? 30*31 = 930

10. You try it! What conjecture can you make about the sum of the first 30 odd numbers?

11. Use the Data Sales of backpacks at a nationwide company decreased over a period of six consecutive months. What conjecture can you make about the number of backpacks the company will sell in May?

12. You are wrong! To prove a conjecture WRONG, all you need is ONE counterexample. Counterexample is an example that shows a conjecture is incorrect

13. Prove me Wrong! If the name of a month starts with the letter J, it is a summer month. You can connect any three points to form a triangle.

15. Practice Problems Page 85-87 #7-37 (odd) #38-55

16. At the Rainbow Apartments, the trim is painted a different color on each floor. Use the clues below to find out what color the trim is painted on each floor. CLUES: – The blue trim is on a higher floor than the green trim, but on a lower floor than the one painted yellow. – The pink trim is on the floor between the one with yellow trim and the one painted blue. – The green trim is on the lower floor than the one with lavender trim.

17. Decide who is twins: 1.All sets of twins consist of a boy and girl. 2.Anna and her twin arrived on Monday 3.Al isn’t Anna’s twin 4.Cal and his twin arrived on Monday. 5.Sam arrived on Friday, but not with Jill 6.Nick and Ellen are twins. They arrived the day after Dana and her twin.

18. AlBobCalNickSamMonTuesWedThursFri Anna Beth Dana Ellen Jill Mon Tues Wed Thurs Fri

19. Ticket out! What are the next two terms in each sequence? 1)7, 13, 19, 25,… 2) 3)What is a counterexample for the following conjecture? All four-sided figures are squares.