Identify parallel lines, perpendicular lines, skew lines, and parallel planes. Identify corresponding angles, alternate interior angles, alternate exterior angles, and consecutive interior angles.

1. Parallel Lines & Transversals
The student is able to (I can):
• Identify parallel lines, perpendicular lines, skew lines, and
parallel planes
• Identify• Identify
— Transversals
— Corresponding angles
— Alternate Interior Angles
— Alternate Exterior Angles
— Consecutive Interior Angles

2. parallel lines
perpendicular
Coplanar lines that do not intersect
Two coplanar lines that intersect at right
m
n
m n
perpendicular
lines
Two coplanar lines that intersect at right
angles (90˚)
f
g
f ⊥ g

3. skew lines
parallel planes
Noncoplanar lines that do not intersect
Planes that do not intersectparallel planes Planes that do not intersect
R
S
Plane R Plane S

4. transversal A line that intersects two coplanar lines at
two different points
r
s
t

5. corresponding
angles
Angles that lie on the same side of the
transversal t, on the same sides of lines r
and s
Example: ∠1 and ∠5
3
1
2
∠1 ≅ ∠5
∠2 ≅ ∠6
∠ ≅ ∠
t
s
r
Corresponding angles of parallel lines are
congruent.
87 6
5
4
3
1
2
2 6
∠3 ≅ ∠7
∠4 ≅ ∠8
s

6. alternate
interior angles
Angles that lie on opposite sides of the
transversal t, between lines r and s
Example: ∠2 and ∠7 or ∠4 and ∠5
r
s
t
interior
4
3
1
2 ∠2 ≅ ∠7
∠4 ≅ ∠5
Alternate interior angles of parallel lines
are congruent.
s
8
7 6
5

7. alternate
exterior angles
Angles that lie on opposite sides of the
transversal t, outside lines r and s
Example: ∠1 and ∠8
r
t
exterior8
7
4
3
2
Alternate exterior angles of parallel lines
are congruent.
sexterior
6
5
1
2
∠1 ≅ ∠8
∠4 ≅ ∠5

8. consecutive
interior angles
Angles that lie on the same side of the
transversal t, between the lines r and s
(sometimes called same-side angles).
Example: ∠3 and ∠5
r
t
interior
43
1 2
Consecutive interior angles of parallel lines
are supplementary.
s
interior
87
65
m∠3 + m∠5 = 180˚
m∠4 + m∠6 = 180˚

9. 1. Find the measures of the
numbered angles if
m∠8 = 125˚
2. List each angle pair
corresponding angles
alt. interior angles
1 2
3 8
Examples
alt. interior angles
alt. exterior angles
consecutive interior angles
4 5
6 7

10. 1. Find the measures of the
numbered angles if
m∠8 = 125˚
2. List each angle pair
corresponding angles
∠1 & ∠4; ∠2 & ∠5;
∠3 & ∠6; ∠8 & ∠7
1 2
3 8
Examples
m∠1 = 125˚; m∠2 = 55˚;
m∠3 = 55˚; m∠4 = 125˚;
m∠5 = 55˚; m∠6 = 55˚;
m∠7 = 125˚
∠3 & ∠6; ∠8 & ∠7
alt. interior angles
∠3 & ∠5; ∠8 & ∠4
alt. exterior angles
∠1 & ∠7; ∠2 & ∠6
consecutive interior angles
∠3 & ∠4; ∠8 & ∠5
4 5
6 7