Lesson 4: Angle Measure
» Degree- the unit of measurement for an angle
» Ray- a part of a line which has one endpoint and one end
that extends infinitely (name with the endpoint first and then
any other point on the ray)
» Opposite rays- two rays that share an endpoint and extend in
opposite directions (together they make a line)
» Angle- formed by two non-collinear rays that have a common
endpoint
» Sides of an angle- rays
» Vertex- the common endpoint of the rays of an angle
» Angle Bisector- a ray or line that divides an angle into two
congruent angles
A
Angle:
B
4
C
-B is the vertex
-ray BA and ray BC are the sides(
BA and BC )
-Angle names:
CBA
ABC, 
B, 4
-Angle bisector : makes 2
congruent angles
Name
Measure
Right
Angle
90
Acute
Angle
Less than
90
(0 < x < 90)
Obtuse Between
Angle 90 and
180
(90 < x < 180)
Model
A. Name all angles that have
B as a vertex.
B. Name the sides of 5.
C.
A. Measure TYV and classify it as right, acute, or
obtuse.
B. Ray YT bisects angle SYU. Angle TYS = 2x-24, angle UYT =
x+16.
Find x and the measure of angle SYU.