3.1a: Transversals and
Angle Pairs
Every man
man dies,
dies, not
not every
every man
man really
really lives.
lives.
Every
-William Wallace
Identifying Angles
Transversal: A line that intersects two coplanar lines at two distinct
points.
l
a
b
m
k
c
How many angles are formed by a transversal?
Identifying Angles
Alternate Interior Angles: Nonadjacent interior angles
that lie on opposite sides of the transversal.
Same-Side Interior Angles: Angles that lie on the same
side of the transversal between the two lines it intersects
Corresponding Angles: Angles that lie on the same side
of the transversal in corresponding positions relative to
the two lines it intersects
Identifying Angles
5
1
6
Alternate Interior Angles:
1 and 2 are alternate interior angles
3
Also:
4
2
7
8

Same-Side Interior Angles:
 1 and 4 are same-side interior angles
Also:

 Angles:
Corresponding
1 and 7 are corresponding angles
Also:

Identifying Angles
Alternate Exterior Angles: Nonadjacent exterior angles
that lie on opposite sides of the transversal.
Same-Side Exterior Angles: Angles that lie on the same
side of the transversal outside of the two lines it intersects
Identifying Angles
5
1
6
4
2
7
8
Alternate Exterior Angles:
5 and 8 are alternate exterior angles
Also:
3

 Same-Side Exterior Angles:
5 and 7 are same-side exterior angles
Also:


Let’s Apply What We Have Learned, K?
Name the transversal and the two lines that form each angle pair.
Then name the angle pair.
1) 1 and 2
A
6
1
3
C 4
2
5
D
B
2) 5 and ACD
3) ABD and CDB
You Guys Try Some
Give a name for the angle pairs given.
1) 8 and 4
1
3
5
7
6
2
4
2) 4 and 5
3) 5 and 3
4) 3 and 2
8
5) 2 and 7
6) 7 and 1
You Guys Try Some
Give a name for the angle pairs given.
1) 8 and 4
1
3
5
7
6
8
2
4
2) 4 and 5
3) 5 and 3
4) 3 and 2
5) 2 and 7
6) 7 and 1
3.1a: Transversals and
Angle Pairs
HOMEWORK: p.131 #1-8, 19-22
TERMS: transversal, alternate interior (exterior) angles, sameside interior (exterior) angles, corresponding angles
Every man dies, not every man really lives.
-William Wallace