1. Section 1-4 Angle Measure
Geometry Notes
Section 1-4 Angle Measure

2. Definition
A ray is a part of a line with an endpoint that extends forever in one direction. A. .B

3. .A .B Table Ray Drawing Facts has a beginning but not end Naming
AB or ray AB
Named by
Letter on endpoint first then another point on the ray .B

4. Definition
Opposite rays – two rays that share the same endpoint but extend in two opposite directions.
R S T
*SR and ST are opposite rays*

5. Definition
An angle is formed by two rays that share a common endpoint and nothing else.
The two rays that make the angle are called the sides of the angle.
The endpoint is called the vertex.
B is the vertex.
BT and BQ are the sides.

6. Table Drawing Facts Naming Named by Angle
Made of 2 noncollinear rays w/a common endpoint
Can be measured in degrees
Naming
Named by
1.one point from one side then the vertex then a point from the other side,2. by the vertex,3. by a numbered angle

7. What do angles do? Angles divide planes into 2 parts.
1. interior of an angle
2. exterior of an angle
Points D and E are in the interior
Point F is in the exterior

8. Classifying Angles by Measure
If x is measure of the angle in degrees:

9. Definition
Congruent angles are angles that have the same measurement.
congruent

10. Definition AD is an angle bisector
An angle bisector is a ray that cuts an angle into two congruent angles.
AD is an angle bisector

11. Now it’s time for some heavy lifting!
Hwk pg 34
#’s 12-33,35-36