Complementary and Supplementary Angles 4'1

1
Complementary and Supplementary Angles (4.1)

• Perpendicular lines -

Lines that intersect at 90? angles
C
0

• Complementary Angles -

Angles that add up to 90?
1 0
S

• Supplementary Angles -

Angles that add up to 180?
2
Example
a) Whats the complement of a 63? angle?
I. 90 63 27?
II. 63 x 90?
- 63
- 63
x 27?
a) Whats the supplement of a 97? angle?
I. 180 97 83?
II. 97 x 180?
- 97
- 97
x 83?
How is a straight angle similar to
supplementary angles?
3
Example
GIVEN
B
2x 26
42
E
Find the value of x.
2
1
W
42 2x 26 90
( )
2x 68 90
- 68
- 68
2x 22
2
2
x 11
4
Example
multiplication
addition
The sum of an angle and three times its
complement is 200. Whats the angle?

angle 3( complement ) 200
What is the complement of 20?
a measure of an angle
What is the complement of 40?
What is the complement of 65?
a 3 ( 90 a ) 200
What is the complement of 72?
a 270 3a 200
What is the complement of a?
270 2a 200
- 270
- 270
a 35?
2a -70
-2
-2
5
Vertical Angles (4.2)

• DEF A pair of angles which are not adjacent
  and are formed by 2 intersecting lines

• ?1 ?3 are vertical angles ?2 ?4 are
  vertical angles

180 145 35
3

• Vertical angles are ?

180 35 145
180 35 145
2
4
1
35
If m?1 35?, find the rest of the angles using
straight line idea
6
Example
1
3
2
164?
m?1
m?2
m?3
?
?
?
164?
16?
16?
7
Example
A
2x 30
GIVEN
C
2
40
3
1
O
Find the value of x.
B
Suggestions?
m?2 m?AOC m?3 180
2x 30
90
40 180
2x 160 180
x 10
- 160
- 160
2x 20
2
2
8
Homework
p. 200, 3 - 6, 10 - 12, 16-18 p. 208, 4 -
10, 21, 23