Download Geometry 1-3 Angle Basics

Geometry 1-3 Basics of Angles
Angle- a figure formed by two rays with a common endpoint.
Interior of an angle- in
between the sides of
the angle.
Exterior of an
angle- outside
of the angle.
Vertex- The common endpoint of an
angle’s rays (plural: vertices).
Types of Angles
• Acute angle: less than 90°
• Right angle: exactly 90°
• Obtuse angle: more than 90°, less than 180°
• Straight angle: exactly 180 °
Naming Angles
•
Angles can be named three ways:
1. By its vertex R
2. By a number 1 (if it has one)
3. By a point on each ray and the vertex
SRT or
TRS (vertex in the middle!)
S
Best, safest way!
R
1
T
More Vocab.
• Congruent angles- angles that have the same
measure.
• Angle bisector- A ray that divides an angle into
two congruent angles
A
Congruent angles:
ARW  LRW
Angle bisector: RW
W
40°
40°
R
L
Using a Protractor
WRS =
TRV =
W
R
Q
S
T
V
U