Math 9

1. A
B
C
D
mABC = 14x + 2, mCBD = 6x + 1, mABD = 25x – 27
WARMUP -
x = 6 mABC = 86 mCBD = 37 mABD = 123
mABC + mCBD = mABD
14x + 2 + 6x + 1 = 25x – 27
20x + 3 = 25x – 27
3 = 5x – 27
30 = 5x
6 = x
mABC = 14x + 2
mABC = 14(6) + 2 = 86
mCBD = 6x + 1
mCBD = 6(6) + 1 = 37
mABD = 25x - 27
mABD = 25(6) - 27 = 123

2. What are some
special angle
relationships?
AGENDA:
• WARMUP
• REVIEW ANGLES FROM WEDNESDAY
• SPECIAL ANGLE PAIRS
• TEST FRIDAY

3. Complementary Angles
Definition: two angles whose measures have
the sum of 90.
Complementary Angles may or may not be
Adjacent Angles.
35
55
20
70

4. Supplementary Angles
Definition: two angles whose measures have
the sum of 180.
Supplementary Angles may or may not be
Adjacent Angles.
125
55
110 70

5. Linear Pair
Definition: two supplementary, adjacent
angles.
Linear Pair = A Pair of Angles that forms a Line.
120
60

6. Vertical Angles
Definition: two non-adjacent angles formed
by intersecting lines.
1
2
3
4
1 and 2 are vertical angles.
3 and 4 are vertical angles.

7. What do you notice?
1
2
3
4
Theorem: Vertical Angles are Congruent.
12
34

8. Applying new concepts with Algebra…
8x + 6
10x - 18
Find x.
We know vertical angles are congruent; therefore the
measure of vertical angles are equal and we can set these
two expressions equal to one another.
10x – 18 = 8x + 6
2x = 24 x = 12
B
A Q
C
D
102
102

9. x
4x
What relationship do we see here?
Complementary Angles
x + 4x = 90
5x = 90
x = 18
18
72

10. Supplementary Angles
6x+7
4x+3
4x+3 + 6x+7 = 180
10x + 10 = 180
10x = 170
x = 17
109
71

11. CHECK FOR UNDERSTANDING
I’m Collecting this for a grade!!
P. 71 #15, 16, 20, 21
P. 72 #37
P. 79 #28, 29
P 80 #54, 55