3.1 – Lines and Angles

Vocabulary Parallel Lines: Two lines that are

coplanar and do not intersect Skew Lines: Lines that do not

intersect and are not coplanar Parallel Planes: Two planes that do

not intersect

Parallel and Perpendicular Line Postulates

Parallel Line Postulate:If there is a line and a point not on the line, P

then there is exactly one

line through the point

parallel to the given line.

Parallel and Perpendicular Line Postulates

Perpendicular Line Postulate:If there is a line and a point not on the line,

P

then there is exactly oneline through the point perpendicular to the given line.

Transversal – a line that intersects two or more coplanar lines at

different points.

Transversal

Alternate Interior Angles

A and B are called Alternate Interior Angles

Consecutive Interior Angles

C

D

C and D are called

Consecutive Interior

Angles*

* Consecutive Interior Angles are sometimes called Same Side Interior Angles

Corresponding Angles

E and F are called

Corresponding Angles

Alternate Exterior Angles

G and H are called Alternate Exterior Angles

#1: Identifying Angles formed by a Transversal

1

2

What types of angles are demonstrated here?

Answer: Alternate Exterior Angles

#2: Identifying Angles formed by a Transversal

3

4

What types of angles are demonstrated here?

Answer: Alternate Interior Angles

#3: Identifying Angles formed by a Transversal

5

6

What types of angles are demonstrated here?

Answer: Consecutive Interior Angles

#4: Identifying Angles formed by a Transversal

5

6

What types of angles are demonstrated here?

Answer: Corresponding Angles