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Geometry Notes
Section 1-4 Angle Measure
Definition
 A ray is a part of a line with an endpoint that
extends forever in one direction.
.
A
.
B
Table
Ray
Drawing
Facts
.
A
.
B
has a beginning but not
end
Naming
AB or ray AB
Named by
Letter on endpoint first then another
point on the ray
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*
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.
Table
Angle
Drawing
Facts
1.
2.
Naming
Named by
Made of 2 noncollinear rays w/a
common endpoint
Can be measured in degrees
B, TBU , UBT , 1
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
What do angles do?
Angles divide planes into 2 parts.
1. interior of an angle
2. exterior of an angle
1. Points D and E are
in the interior
2. Point F is in the
exterior
Classifying Angles by Measure
•If x is measure of the angle in degrees:
Definition
 Congruent angles are angles
that have the same
measurement.
mBAD  mCAD
congruent
Definition
 An angle bisector is a ray that cuts an angle
into two congruent angles.
AD is an angle bisector
Now it’s time for some heavy lifting!
Hwk pg 34
#’s 12-33,35-36