SELECT ANSWERS TO HOMEWORK
8)a) b, c, T=a
b) b, d, T=a
9)a) AB, EC and T=AC
b) AC , ED and T= CE
10) a) FG, HK and T=IF
b) GF, HK and T=GJ
11) Corr.
12) Alt Int 13) SSI
14) Alt. Int
15) SSI
16) Corr.
18) SSI
19) Corr
20) SSI
21) Alt. int 22) Alt. Int
23) Corr
3-2 PROPERTIES OF PARALLEL
LINES
POSTULATE
If two parallel lines are cut by a transversal, then
corresponding angles are congruent
 What 4 pairs are congruent?

1 2
3 4
5 6
7 8

Note the arrows on the lines: means they are
parallel.
THEOREM
If two parallel lines are cut by a transversal, then
alternate interior angles are congruent
 What 2 pairs of angles are congruent?

1 2
3 4
5 6
7 8
THEOREM
If two parallel lines are cut by a transversal, then
same-side interior angles are supplements.
 SSI starts with “S” and is the only one that is
SUPPS!!
1 2
3 4

5 6
7 8

What 2 pairs are supps?
THEOREM

If a transversal is perpendicular to one of two
parallel lines, then it is perpendicular to the
other line as well.
x  2y
70  2 y
y  35
EXAMPLE

x  110  180
x  70
Find x, y, and z.
x
2y
110
2z
110  2 z
z  55
TOO

x  20
y  40
Find x, y, and z.
z  140
z
y
2x
40
HOMEWORK

Page 80-82 #1-16, 20, 21
#20 and #21 are 4 Step Proofs (See whiteboard)
 See overhead for help with some!!


Flash Cards

3 Theorems and a Postulate





Corr angles
SSI angles
Alt. Int angles
If perp. to one line then perp. to another
Draw a picture on the flashcards!!