1. Angle Relationships
Chp A pg

2. Definitions Degree – 1/360 of a turn around a circle Examples:
“Do a 180 or a 360”
A 180 is a half circle or a half turn
A 360 is a complete circle or full turn.
Degrees are used to measure angles.

3. Definitions Ray – a part of a line
Rays are named by using the endpoint first and then another point on the ray A B AB

4. Opposite Rays - Line These are called opposite rays.
If you choose a point
on a line, that
point determines
exactly two
rays
These are called opposite
rays.
Thus a line can be thought of as two opposite rays
This can also be called a straight angle.

5. Angle An angle is formed by two rays with a common endpoint
We name angles with the symbol “” and
three letters, the vertex letter, or a number R
The rays are called
sides of the
angle
Point C lies
in the
interior of
the angle C
RST S 1 D
Point D lies on the
exterior of the angle 1 S
The common
endpoint is the vertex. T

6. Classification of Angles
Right Angle R
Acute Angle
mGSH = 90° G
mRDB  90°
an angle with
measure equal
to 90° B D
an angle with measure less
than 90° S H
This symbol means 90° J
Obtuse Angle
an angle with measure greater than 90° and
less than 180°
90°  m  JAM  180° A M

7. Congruent Angles Angles that have the sameF
Arcs on the figure indicates
which angles are congruent.
30° C D
Angles that have the same
measure are called congruent
angles. B
30° A
This statement,  ABD   CBF, reads
angle ABD is congruent to angle CBF

8. Answer this? G A B Name all angles that have B as a vertex. 7 5 6
 ABG
 5 M
 6 D
 7 K 4 3
Name the sides of  5. E
BG and BE or BF V F
What is another name for  6?
 FBV,  DBE,  VBF, or  EBD

9. Complementary and Supplementary Angles
Complementary Angles – Two angles whose measures add to 90°
Find the measure of  C if C and D are complementary and m D = 50°
m C + m D = 90°
m C + 50° = 90° m C = 40°

10. Supplementary Angles
Supplementary Angles – Two angles whose measures add to 180°
m  A + m B = 180°
If m B = 110°, find m A