Download Sec. 2.7: Prove Angle Pair Relationships

Lesson 14.1: Angles Formed by
Intersecting Lines
Geometry Vocab Review
Complementary Angles are two angles whose
measures add up to 90 degrees.
Supplementary Angles are two angles whose
measures add up to 180 degrees.
Congruent Angles are angles that have equal
measure.
Linear Pairs of Angles
When two lines intersect, they form four angles.
The angles that together form a straight line are
called linear pairs of angles.
Angle 1 and 2,
Angle 2 and 3,
Angle 3 and 4,
and Angle 4 and 1
are linear pairs of angles.
Linear Pair Theorem
Linear pairs of angles are supplementary.
Since angles 1 and 2
are a linear pair, then
they are supplementary
by the Linear Pair Theorem.
The same can be said about any other linear pair
Vertical Angles
When two lines intersect to form four angles,
the angles that are opposite each other are
called vertical angles.
Angles 1 and 3 are vertical angles.
Angles 2 and 4 are vertical angles.
Vertical Angle Theorem
If two angles are vertical angles, then they are
congruent.
by vertical angle theorem
Prove the Vertical Angle Theorem