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Susan Chaffee Geometry Section 3.2 Spring 2009 Lesson 1 – Section 3.4 Unit: Chapter 3 Parallel and Perpendicular Lines Lesson: Section 3.4 Goals: To classify triangles and find measure of angle using triangle angle-sum and exterior angles. Lesson Objectives: Enduring Understanding: Materials and/or Special Notes: Lecture materials (computer): Prior Knowledge: Write on the board: Section 3.4…Parallel Lines and the triangle angle-sum theorem Motivation: Review: Lesson Activites : 1) Student activity. Draw a triangle on your paper. Measure each angle. Add them and what do you notice. 2) SB 1: Triangle sum theorem. a. 3) SB 2: Triangle types a. 4) Work exercises 1-5. Work exercises 6-7 Define exterior angle of a polygon. Angle formed by one side and an extension of the adjacent side. a. Student activity. Use triangle cutout to place angles 2 and 3 next to 1. What is the sum of 1,2,3 ? b. Show algebraically. Angle2 + angle 3 = 180 – angle 1. If we call the outside angle 4. Then angle 4 = 180 – angle 1. 5) Worksheet: #12-15