1. Entry Task Write down your age Multiply it by 10 Add 8 to the product Double that answer and subtract 16 Divide the result by 20 Explain what you notice. Why does it work?

2. Reasoning in Algebra and Geometry 2.5 Learning Target: I can use algebraic properties in geometry to solve problems and justify my steps. I accept postulates and properties to be true

5. P. 902-910 These pages should be booked marked in your text. This is where all theorems and postulates are located that you can use while doing proofs.

6. Proofs - When writing a proof, it is important to justify each logical step with a reason. You can use symbols and abbreviations, but they must be clear enough so that anyone who reads your proof will understand them. Conclusion Definitions Postulates Properties Theorems Hypothesis

7. If a diagram for a proof is not provided, draw your own and mark the given information on it. But do not mark the information in the Prove statement on it. Helpful Hint

8. Proof

9. Table Groups Let’s not worry just yet about a “two column” proof. Let’s see if your group can argue with me and prove this:

12. Writing a Two-Column Proof Write a two-column proof. Given: Prove:

13. Writing a Two-Column Proof

16. Homework Homework– p. 117 #1-13,20 Challenge - #25

21. S T I R