Definitions
Parallel Lines (ll) - coplanar lines that
do not intersect
m
n
m ll n
Skew lines - NONcoplanar lines. They
don't intersect and aren't parallel.
k
j
Title: Oct 4-4:12 PM (1 of 8)
k and j are skew lines
Parallel Planes - planes that do not
C
intersect
B
A
H
G
D
E
F
A line and a plane are parallel if they
do not intersect
a) Name two parallel planes
b) Name a line and a plane that are parallel
Title: Oct 4-4:38 PM (2 of 8)
Theorem:
If 2 parallel planes are cut by a third plane, then the
lines of intersection are parallel.
Draw a picture that represents this theorem
Title: Oct 4-4:46 PM (3 of 8)
Definitions
A transversal is a line that intersects two
or more coplanar lines in different points.
Example: Line t is a transversal of lines h
t
and k.
2
1
3
7
4
5 6
8
h
<1, <2, <7, and <8 are exterior
angles
<3, <4, <5, and <6 are interior
angles
k
Alternate Interior Angles:
Same-side interior angles:
Corresponding angles:
Alternate exterior angles:
Title: Oct 4-4:50 PM (4 of 8)
Classify each statement as True or False
1) A transversal intersects only parallel
lines
False
2) Skew lines are not coplanar True
3) If two lines are coplanar, then they are
parallel False
4) If 2 lines are parallel, then exactly one plane
contains them True
True
Title: Oct 4-4:57 PM (5 of 8)
False
Name the two lines and the transversal
that form each pair of angles
k
1)
1 and
3
2)
3 and
11
3)
10 and
12
56
9 10
13 14
Title: Oct 4-5:00 PM (6 of 8)
11
m
3 4
7 8
11 12
15 16
t
n
Title: Oct 5-10:40 AM (7 of 8)
Classify each pair of angles as alternate
interior angles, same-side interior angles,
or corresponding angles.
1)
2)
3)
4)
5)
<1 and <3 CA
<6 and <7 SSIA
<2 and <7 AIA
<ADE and <DEB SSIA
<BEF and <EGI CA
"Z"
SSIA
"C"
CA
"F"
3 4
7 8
1 2
5 6
A
B
D
C
E
F
G
H
Title: Oct 4-5:05 PM (8 of 8)
AIA
I