10/20 Bell Ringer Step 1: Grab your notes from front. Step 2: Get out your homework Step 3: Write a two-column proof to find x, given 4(x – 9) = 8 Homework: Complete tonight’s homework and study Monday and Tuesday’s notes for QUIZ Tomorrow

10/20 News and Notes Quiz Tomorrow Tracia and James Quod Erat Demonstrandum

10/20 Agenda I CAN use properties of equality to justify statements about geometric figures. 1.Bell Ringer 2.New Material – Agile Mind Example 3.Guided Practice – Pieces of a proof 4.Independent Practice – Name the property. 5.ACT Question of the Day

Today’s Goal Yesterday, we wanted to get used to the format of a proof. Today, we want to apply properties of equality to geometric figures. So that next week we will be able to write proofs of geometric situations.

New Material – Examples For each, provide the property and a brief description of how you know. 1.Symmetric – If they’re equal, they can be on either side of the sign. 2.Reflexive – Line segment = to itself. 3.Transitive – They’re all equal! 4.Division – We’re dividing the big angle into two parts. 5.Subtraction – We’re removing AB from both line segments (subtracting them) 6.Substitution – We’re subbing DE in for BC because they are equal. 7.Multiplication – We’re multiplying both by 2 to show that 2 angle 1s = angle 2.

Guided Practice – Pieces of a Proof StatementReason AC = BDGiven BC = BCReflexive Property of Equality AB + BC = AC CD + BC = BD Segment Addition Postulate AB + BC = BDSubstitution Property of Eq. AB + BC = CD + BC AB + BC – BC = CD + BC – BC Substitution Property of Eq. Subtraction Property of Eq. Simplify AB = CD

Independent Practice You now have all but the last 5 minutes of class to work on your independent practice/homework.

ACT Question of the Day If AB = CD, and CD = EF, write a valid statement (a relationship that is true) about AB and EF and give a reason.