Page 92 - Math Course 1 (Book 2)

Relationships in Angles

Mo. 9

Lesson 5 linear pair
is a pair of adjacent angles with non-common
sides that are opposite rays.

KEY CONCEPTS: ∠DEB and ∠BEC
1. Identify and use special pairs of angles.
2. Identify perpendicular lines. B
3. Interpret f gures using the relationships in C
angles.
E
MO. 9 - L5a D

Special Pairs of Angles complementary angles
are two angles with measures that have a sum of
90 .
o
Vocabulary A-Z ∠1 and ∠2 are complementary

Let us learn some vocabulary ∠PQR and ∠XYZ are complementary.
P Q Y
50 O
1 X 40 O
adjacent angles 2
R Z
are two angles that lie in the same plane, have a
common vertex and a common side, but no
common interior points. supplementary angles
are two angles with measures that have a sum of
o
∠ABC and ∠CBD 180 .
C
∠EFH and ∠HFG are supplementary. ∠M and ∠N
A are supplementary.
C
D H
M
D B 80 o
B A E F G N 100 o

vertical angles Key Concept Angle Points
are two nonadjacent angles formed by two
intersecting lines. Words
Adjacent angles are two angles that lie in the same
plane, have a common vertex and a common side,
∠AEB and ∠CED but no common interior points.
∠AED and ∠BEC
Examples Nonexamples
∠AEB and ∠CED ∠AED and ∠BEC
A ∠AED and ∠BEC

B A
C
A
C
D E D
C
B
D
B Shared interior

84