Grade 8 math

1. Parallel and
Perpendicul
ar Lines

2. Parallel lines are always the same distance
apart. They will never touch.
Parallel lines
“Enemy Lines”

3. Can you find the parallel lines?

4. Perpendicular lines
are two lines that
intersect to form
right angles.
Perpendicular lines
90

5. Can you find the perpendicular
lines?

6. Perpendicular lines
Perpendicular lines are also
intersecting lines because they
cross each other.
Perpendicular lines are a
special kind of
intersecting lines
because they always
form “perfect” right
angles.
90

7. The quadrilateral formed the plane MATH.
Segment MA lies on plane MATH;
segment HT lies on plane MATH
Therefore, MA is coplanar with HT and Segment
MA ∥ HT
Two lines are parallel if :
a. They are coplanar and do not
intersect.
Progres
s:

8. Parallel
lines cut
by
transvers
al
b

9. Corresponding angles are congruent

10. Alternate Interior angles are
congruent

11. Alternate Exterior angles are
congruent

12. Same side Interior angles are
supplementary

13. Same side Exterior angles are
supplementary
Exterior Angles
Same Side of
Transversal

14. If two coplanar lines are perpendicular
to the same line then they are parallel

15. If two lines are parallel to another third line,
then they are parallel to each other

16. Two lines are perpendicular if:
a) Two lines form four right angles

17. Two lines are perpendicular if:
b) Two intersecting lines form a linear pair of
congruent angles

18. Two lines are perpendicular if:
c) If a transversal is perpendicular to the first line, then it is also
perpendicular to the second line parallel to the first line.

19. Example 1
Find the value of x so that the two lines are
parallel
Solution:
24 + 2x = x + 86
2x - x = 86 - 24
x = 62

20. Example 2
Find the value of x so that the two lines are
parallel
Solution:
11x – 9 = 90
11x = 90+9
11x = 99
x = 9

21. Direction: Use the figure at the right. Given: CE || AB,
find the measurement of the following angles:

23. Use the following diagram of parallel lines cut by a transversal
to answer questions 3 through 9.
1. What type of angle pair is ∠1 and ∠5?
A. alternate interior angles
B. supplementary angles
C. corresponding angles
D. alternate exterior angles
E. vertical angles
2. What is the measure of ∠8?
A. 45° B. 145° C. 55° D. 135° E.
155°
3. What is the measure of ∠3?
A. 45° B. 145° C. 55° D. 135° E.
155°
4. What is the measure of ∠6?
A. 45° B. 145° C. 55° D. 135° E.
155°
5. What is the measure of ∠2?