Parallel Lines

Parallel Lines & Transversals

Parallel Lines  A

B

C

D

The symbol

||

is used to indicate parallel lines.

AB

||

CD

 A  C

D

B

AB

|| CD

 A line, ray, or segment that intersects 2 or more COPLANAR lines, rays, or segments. l

 A

EXTERIOR

B

INTERIOR C

D

EXTERIOR

l

m

n

If two parallel lines intersected by a transversal, the interior angles on either side of the transversal are supplementary.

Given: line m I I line n. l is transversal.

The corresponding angle formed by a transversal of two parallel lines are of equal measure

Given: line m I I line n. l is transversal.

The alternate angle formed by a transversal of two parallel lines are of equal measure

Given: line m I I line n. l is transversal.

Parallel Lines w/a transversal AND Angle Pair Relationships

Types of angle pairs formed when a transversal cuts two parallel lines. alternate interior angles- AIA  alternate exterior angles- AEA  corresponding angles - CA  vertical angles- VA 

linear pair of angles- LP