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Section 2-4
Special Pairs of
Angles
Complementary Angles
• Two angles whose measures have the sum of
90 degrees
1and2
are complementary
angles
1
2
Each angle is called the complement of the other.
Ex:
1 is the complement of 2
Supplementary Angles
• Two angles whose measures have the sum of
180 degrees
3and4
3
4
are supplementary
angles.
Each angle is called the supplement of the other.
Ex: 3 is the supplement of 4
Vertical Angles
• Formed when two lines intersect.
Need to know the following theorem:
Vertical Angles are Congruent.
In other words, vertical angles have the
same angle measure.
1
2