Download Module 4 Lesson 2 Angles and Parallel Lines

Module 4 Lesson 2
Angles and Parallel Lines
Parallel Lines
• Lines that are coplanar and NEVER intersect.
– Remember that COPLANAR means on the same plane
These are two parallel lines.
They will keep extending in both
directions and never intersect.
B
A
AE, DH, CG, BF would all be parallel to each other.
AB, DC, HG, EF would all be parallel to each other.
C
D
E
H
AD, BC, FG, EH would all be parallel to each other.
F
G
Parallel Lines
G
H
J
K
Skew Lines
• Lines that are NON-coplanar that NEVER intersect.
– Remember that NON-coplanar means not on the same plane.
B
A
DC and GF would be skew lines.
C
D
AE and HG would be skew lines.
E
H
F
G
You try….
1.
2.
3.
4.
5.
6.
Name a line parallel to XY.
Name a line parallel to WS.
Name a line parallel to UT.
Name a line skew to YZ.
Name a line skew to XR.
Name a line skew to UR.
W
X
Z
Y
R
U
S
T
Transversal
• A line that intersects at least two other lines in two distinct
points.
transversal
Alternate Interior Angles
• A pair of angles that are on opposite sides of the transversal
but inside the two lines.
transversal
1
3
5
7
2
4
6
8
3 and 6 would be alternate interior angles.
4 and 5 would be alternate interior angles.
• When the two lines are parallel, then alternate interior angles
are CONGRUENT.
Alternate Exterior Angles
• A pair of angles that are on opposite sides of the transversal
but outside the two lines.
transversal
1
3
5
7
2
4
6
8
1 and 8 would be alternate exterior angles.
2 and 7 would be alternate exterior angles.
• When the two lines are parallel, then alternate exterior angles
are CONGRUENT.
Corresponding Angles
• A pair of angles that sit in the same corner of the transversal
but on a different line.
transversal
1 and 5 would be corresponding angles.
1
3
5
7
2
2 and 6 would be corresponding angles.
4
6
8
3 and 7 would be corresponding angles.
4 and 8 would be corresponding angles.
• When the two lines are parallel, then corresponding angles
are CONGRUENT.
Consecutive Interior Angles
• A pair of angles that are inside the lines and on the same side
of the transversal.
• Also called same-side interior angles.
transversal
1
3
5
7
6
8
2
4
3 and 5 would be cosecutive angles.
4 and 6 would be consecutive angles.
• When the two lines are parallel, then consecutive angles are
SUPPLEMENTARY.
Examples
Find the measure of angle 1.
1.
2.
56
1
1
91
3.
4.
134
1
85
1
You try….
Find the measure of angle 1.
1.
2.
81
75
1
1
3.
4.
155
101
1
1
You try…
Find x.
1.
2.
Find the measure of the angle in bold.
3.
4.
Answers to You Try slides…
Parallel/Skew Lines
1. WZ, ST, RU
2. ZT, YU, XR
3. RS, XW, YZ
4. XR, WS, RU, ST
5. YZ, UT, WZ, ST
6. YZ, WX, ZT, WS
Angles
1. 105°
2. 81°
3. 155°
4. 101°
Find x.
1. 11
2. 8
Find the angle in bold.
3. 110°
4. 130°