6.1(b) Notes: Exterior Angle Theorem   Lesson Objective: Apply Exterior Angle Theorem CCSS: G.CO.10 Prove theorems about triangles You will need: a pencil, colored pens Real-World App: What is the angle that a bracket makes with a wall? This is Jeopardy!!!: This is the m/ A when m/ B = 42°. A B C

Lesson 1: Exterior Angle Theorem   Draw a line across the page, starting at the left margin.

Lesson 1: Exterior Angle Theorem   Label your loose triangle as shown. Trace the triangle onto your page. Label. Tear off angles 1 and 2 of the loose triangle. 2    1 3 Exterior Angle Theorem:

Lesson 1: Exterior Angle Theorem   Glue your triangle down on to the line. Label the exterior angle / 4 far off the angle as shown. 2 4    1 3  

2 Lesson 1: Exterior Angle Theorem   Place / 1 and / 2 inside exterior / 4 as shown and glue them What do you observe? 2 4    1 3 1 Exterior Angle Theorem: 2

2 Lesson 1: Exterior Angle Theorem   Example: m/ 4 = m/ 1 + m/ 2 Exterior Remote 2 4    Interior 1 3 1 Exterior Angle Theorem: The measure of the exterior angle = the sum of the remote interior angles. 2

Lesson 2: Using the Exterior Angle Theorem

Lesson 2: Using the Exterior Angle Theorem FITNESS Find the measure of / JKL in the Triangle Pose shown.

Lesson 3: Finding Angle Measures in Right Triangles Find m/ 1. Find m/ 2. Find m/ 3. Find m/ 4.

6.1(b): Do I Get It? Yes or No 1. Find m/ 1 on the truck 2. Find the value below. Then find m/ 2. of x in the figure below. Then find the measure of each angle.