This document defines and explains key concepts related to parallel and intersecting lines. Parallel lines are lines on the same plane that do not intersect. A transversal is a line that intersects two or more lines. When a transversal cuts parallel lines, it forms corresponding angles, alternate interior angles, alternate exterior angles, same-side interior angles, and same-side exterior angles that are congruent.

3. l
___ ___ ___ ___
E T I O S L N S A E N U L B
L I N E
l
___ ___ ___ ___
E T I O S L N S A E N U L B

4. is straight
curves, no th
and extends in
directions with
L I N E

5. ___ ___ ___ ___ ___ ____ ___ ___
A T L K P B X R A L E O E L
P A R A L L E L

6. are line
plane
which do n
meet.
P A R A L L E L

7. ___ ___ ___ ___ ___ ___ ___ ___ ___
Q E C T S B G E R A D I N T
I N T E R S E C T

8. two line
meet each
at
one point.
I N T E R S E C
T

10. s
nship
angles
d by
el lines cut
ansversal
bjective
:

11. l
i
k

12. Therefore, lines are
parallel if they are on
the same plane, and
do not intersect with
each other. So parallel
lines should be

13. Two lines
parallel
if and only
are coplana
they
PARALLEL
LINES

14. line that
sects two or
ore lines
TRANSVERSAL

15. Transversal
1 2
3
4
6
7
8
5
l
i
k

16. 1 2
3
4
6
7
8
5
l
i
k
Interior Angles
- are angles in
the inner part
of the parallel
lines cut by a
transversal.

17. Exterior Angles
1 2
3
4
6
7
8
5
- are angles in
the outer part
of the parallel
lines cut by a
transversal
i
k
l

18. Pair of Angles:
• corresponding angles
• alternate interior angles
• alternate exterior angles
• same side interior angles
• same side exterior angles.

19. 1 2
3
4
6
7
8
5
l
i
k
Correspondi
ng Angles
- are two angles in
the same relative
position on two
parallel lines when
those lines are cut
by a transversal.
- Congruent angles

20. 1 2
3
4
6
7
8
5
i
k
Alternate Interior
Angles
- are two non-
adjacent interior
angles in the
opposite sides of
the transversal.
- Congruent angles

21. Alternate Exterior
Angles 1 2
3
4
6
7
8
5
- are two non-
adjacent exterior
angles in the
opposite sides of
the transversal.
- Congruent angles

22. Same Side Interior
Angles 1 2
3
4
6
7
8
5
- are angles that
are formed in the
inner part of the
same side of the
transversal.
- Supplementary angles

23. Same Side Exterior
Angles
- are angles that
are formed in the
outer part of the
same side of the
transversal.
1 2
3
4
6
7
8
5
- Supplementary angles

24. Transversal
120° 2
3
4
6
7
8
5
l
i
k

25. Game Time!

27. Direction:
• Class will be divided into 2
groups
• All members must have a
corresponding number
• As I call a number,

28. Direction:
• I’ll show on the screen the
angles or pair of angles,
then write your answer on
the board
• 1st member to answer will

29. A
B
C
D
F
E
H
G
m
n
o

30. A
B
C
D
F
E
H
G
m
n
o

31. A
B
C
D
F
E
H
G
m
n
o

32. A
B
C
D
F
E
H
G
m
n
o

33. A
B
C
D
F
E
H
G
m
n
o

34. A
B
C
D F
E
H
G
m
n
o

35. A
B
C
D
F
E
H
G
m
n
o

36. A
B
C
D
F
E
H
G
m
n
o

37. A
B
C
D
F
E
H
G
m
n
o
125°

38. Generalization
• When can we say that two lines are parallel to each
other?
• What do you call a line that intersects two or more
lines?
• How about the angles in the inner part of the parallel
lines cut by a transversal?
• How about the Outer part of it?