Lesson 8.2: Naming & Measuring Angles Standard: MG 3.1, MG 3.4 Objective: Name angles. Measure angles. Find the complement and supplement.

A B C Vertex Point A Sides Angle Name Angle Angle - An angle has two rays and an endpoint called a vertex.Angles We name angles using the VERTEX and other letters around it. The Vertex letter always goes in the center.

Angles Identify the vertex and name the angle. ( This one has 3 angles!)Identify the vertex and name the angle. ( This one has 3 angles!) 1)2)

Angles that measure less than 90. Angles that measure more than 90 and less than 180. Angles that measure exactly 90. Types of Angles Acute - Right - Angles that measure exactly 180. Obtuse Obtuse - Straight -

Types of Angles Identify the type of angle.Identify the type of angle. 1)3) 2)4)

Complementary Angles a b - Angles whose sum is 90. x y Complementary angles may not be adjacent. Complementary Angles Example: The complement would be 90 – 40 =50

Find the complement of the angle measures below. 1) 30 2) 49 3) 80 4) Has no complement Angles can’t be negative.Think about it!

Supplementary Angles k t - Angles whose sum is 180. b c Supplementary angles may not be adjacent. Supplementary angles need to add up to 180 because that is the definition. Example: To find the supplement, = 70

Find the supplement of the following... 1) 18 2) 104 3) 158 4)

Using a Protractor to Measure Angles Steps 1) Line up the protractor to the angle’s baseline.

Using a Protractor to Measure Angles Steps 1) Line up the protractor to the angle’s baseline. Vertex in center of hole

Using a Protractor to Measure Angles Angle Opens Right Use Inside Numbers Steps 1) Line up the protractor to the angle’s baseline. 2) Read the measure of the other ray. Vertex in center of hole Baseline on zero degrees 45

Using a Protractor to Measure Angles Angle Opens Right Use Inside Numbers Steps 1) Line up the protractor to the angle’s baseline.

Using a Protractor to Measure Angles Angle Opens Right Use Inside Numbers Steps 1) Line up the protractor to the angle’s baseline. 2) Read the measure of the other ray. Vertex in center of hole Baseline on zero degrees 60 Angle Opens Left Use Outside Numbers