Lesson 1.4Measuring and

Classifying Angles

Objective

• Name, measure, and classify angles

Standard 1.0

• Students will demonstrate understanding by identifying and giving examples of undefined terms, axioms, theorems, and inductive and deductive reasoning

Angle

• Consists of two different rays with the same endpoint.

Vertex

• Endpoints of rays in a angle

Angle A or A

The angle with sides AB and AC can also be named orBAC CAB

Example

• Name 3 angles

Degrees are the unit of measure for an angle

• Angles are measured in degrees because they are a portion of a circle.

Classify Angles

Use a protractor to measure angles

Angle Addition Postulate

• If P is in the interior of , then the measure of is equal to the sum of the measures of and

RSTRSTRSP PST

RSTPSTRSP

Example Problem

Indy Practice

Congruent Angles

• Angles with the same measure

A B

BA

BA

Angle Bisector

• A ray that divides an angle into two angles that are congruent

Example

Practice