Page 42 - SPARK OF MATH book 6
P. 42
Pairs of angles.
In geometry, pairs of angles can relate to each other
in several ways.
When two or more lines or rays intersect, pairs of
angles are formed.
Complementary Angles
Two angles are called complementary angles if the
sum of their measurements equals 90
o
(right angle). One of the complementary angles is
said to be the complement of the other.
ABC is the complement CBD
Supplementary Angles
Two angles are called supplementary angles if the sum
o
of their measurements equals 180 (straight angle).
One of the supplementary angles is said to be the
supplement of the other. ABC is the supplement CBD
Vertical Angles
Two pairs of angles are formed by two intersecting lines. 90 o
Vertical angles are opposite angles in such an intersection.
Vertical angles are equal to each other.
Knowing the relationship of angle pairs will help you
calculate the measurement of the angles. Review
with a classmate the following example:
G
The measurement of <DBE= 90° because
The measurement of <GBC= 60° because
The measurement of <GBA= 120° because
The measurement of <DBC= 120° because
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