M.G. 2.1 Identify angles as adjacent, vertical,
complementary and supplementary.
Objective-- Students will identify angles as complementary
and supplementary and solve problems with an unknown
angle from given information about them by finding a
missing angle and scoring an 80% proficiency on an exit slip.
Quick Check!
1) On your whiteboards, show me what a pair of complementary
angles look like and how many degrees they measure.
2) Now, show me on your whiteboards, what a pair of
Supplementary angles look like and how many degrees they measure.
Supplementary angles add up to
180º.
40º
120º
60º
Adjacent and Supplementary
Angles
140º
Supplementary Angles
but not Adjacent
Complementary angles add up to
90º.
30º
40º
50º
60º
Adjacent and Complementary
Angles
Complementary Angles
but not Adjacent
Remember our Objective…
identify angles as
complementary and
supplementary and solve problems with
Students will
an unknown angle from given information about
them by finding a missing angle and scoring an
80% proficiency on an exit slip.
Remember: Two angles are supplementary if the sum
of their measures is 180 degrees. Each angle is the
supplement of the other.
1
20
160
These are supplements of each other
because their angles add up to 180.
2
3 STEPS for Finding Missing
Angles:
1) First, create an addition equation by adding both angles.
1) The sum of the two angles will equal
90° for Complementary Angles and
180° for Supplementary Angles.
3) Solve the equation using the inverse rules!
Think…Pair… Share…
How are angles part of our outside world?
If there were no angles, how do you think our world would
be different?
What other subjects can you make connections with that also use
Angles?
Example 1
an equation.
Find the value of x by making
x
20
x + 20 = 180
x = 160
Example 2
Find the value of x by writing
your equation.
x
65
x + 65 = 180
x = 115
Two angles are complementary if the sum of their
measures is 90 degrees. Each angle is the complement
of the other.
1
2
30
60
These are complements of each other
because their angles add up to be 90.
Example 3
Find the value of x.
x
x + 15 = 90
x = 75
15
Now, think of what we talked about today.
1
5
2
4
3
Are angles 4 and 5 supplementary angles?
no
Are angles 2 and 3 complementary angles?
no
Are angles 4 and 3 supplementary angles?
yes
Are angles 2 and 1 complementary angles?
yes
FOLDABLE ON ANGLES:
Measures less than
Measures exactly
90 degrees
90 degrees
Measures more
than 90 degrees
and less than 180
degrees.
Vertical Angles are
the angles opposite
each other when
two lines cross
Examples
Two angles whose
sum is equal to
90 degrees
Measures exactly
180 degrees
Two angles that
share a same side
and same vertex
Two angles whose
sum is equal to
180
Degrees.
Examples
Example 4
Find the value of x.
(4x + 3)
(x - 8)
(4x + 3) + (x - 8) = 90
5x - 5 = 90
5x = 95
x = 19
Example 5
Find the value of x.
(7x  10)
3x
(7x + 10) + 3x = 180
10x + 10 = 180
10x = 170
x = 17
Think back to last class…
1
5
2
4
3
Are angles 1 and 2 a linear pair?
no
Are angles 1 and 3 adjacent angles?
no
Are angles 3 and 4 a linear pair?
yes
Are angles 2 and 3 adjacent angles?
yes
identify
angles as complementary
and supplementary and solve
Remember…Students will
problems with an unknown angle from
given information about them by finding
a missing angle and scoring an 80%
proficiency on an exit slip.
Figure 1find the missing angles you may use a
protractor to draw it!
T
X
40
50
Z
R
Q
V
40
S
Y
S
Figure 2: find the missing angles
you may use a protractor to
draw it!
E
A
B
w
20
z
x
y
G
C
F
D
Figure 3
P
N
X4525°
45
M
L
20
Q
R
P- 45°