1 6 Exploring Angles Objectives To identify angles

1 -6 Exploring Angles Objectives: To identify angles and classify angles. To use the Angle Addition Postulate to find the measure of angles. To identify and use congruent angles and the bisector of an angle.

Vocabulary • • Ray Angle Opposite Rays Sides Vertex Interior Exterior • Degrees • Measure • Congruent Angles

Definition of Ray • A ray extends indefinitely in one direction. F E D • How to name a ray.

Definition of Opposite Rays • If you choose any point on a line, that point determines exactly two rays called opposite ray. Opposite rays are collinear. I G H

Definitions of Angles, Sides, Vertex • An angle is a figure formed by two noncollinear rays with a common endpoint. The two rays are called the sides of the angle. The common endpoint is called the vertex. A 1 B C

Naming Angles • How many angles are there? Name them all. Q R P S

Example 1 a. What other names could be used to identify ? b. Name the vertex of. c. What are the sides of .

Definition of Interior and Exterior • An angle separates a plane into three distinct parts, the interior of the angle and the exterior of the angle, and the angle itself.

Postulate 1 -4 Angle Addition Postulate

Example 2 What is the measure of angle DAC?

Definition of Right, Acute, and Obtuse Angles

Definition of Congruent Angles Congruent angles are angles that have the same measure.

Homework 1 -6 Worksheet