1. GT Geom Drill #28 10/24/13
Are These Lines Parallel?
a
40º 140º
t
b

2. Are These Lines
Parallel?
a
40º
140º
t
b

3. Are These Lines
Parallel?
a
80º
b
80º
t

4. Are These Lines
Parallel?
a
70º
70º
t
b

5. Yes or No!!
Are the converses of the
corresponding angles
postulate, alternate int. angles
thm, alt. Ext. angles thm and
same side interior angles thm
true?

6. Yes or No!!
Are the converses of the
corresponding angles postulate,
alternate int. angles thm, alt.
Ext. angles thm and same side
interior angles thm true?

7. OBJECTIVE
To PROVE THAT
LINES ARE
PARALLEL.

8. Converse of the Corresponding
Angle post
If two lines are cut by a
transversal such that
corresponding angles are
congruent, then two lines
are parallel.

9. Converse of the Alternate
Interior Angle Theorem
If two lines are cut by a
transversal such that
alternate interior angles
are congruent, then the
lines are parallel.

10. Converse of the Same Side
Interior Angle Theorem
If two lines are cut by a
transversal such that same
side interior angles are
supplementary, then the
lines are parallel.

11. THEOREM
If two lines are cut by a
transversal such that
alternate exterior angles
are congruent, then the
lines are parallel.

12. STATE EARLIER THEOREM
a
b
t

13. THEOREM
If two lines are
perpendicular to the same
line, then the lines are
parallel to each other.

14. NEW THEOREM
If a || b
and
a || c,
then?????????

15. THEOREM
If two lines are parallel
to the same line, then
the lines are parallel
to each other.

16. Conclusions
1) State the converses
 2) If two lines are
perpendicular to the same
line then…
 3) If two lines are parallel
to the same line then...


17. HOMEWORK
Finish classwork
.

18. CLASSWORK
Proving Lines are Parallel
#1-15

19. Assessment
Complete ditto:
“Proving Lines are
Parallel II”