This document provides examples and explanations for using algebra to solve for unknown angle measures involving complementary and supplementary angles. It begins with warm up problems labeling angle pairs as complementary, supplementary, or neither. Examples are then worked through step-by-step to find missing angles given information about one angle. Students are assigned complementary, supplementary, or 3 times larger problems to work through independently and explain to the class. Homework and an upcoming test are assigned before ending.

1. 1-6: Algebra
and Angles
I CAN:
Use algebra to solve for
unknown angle measures.

2. Warm Up 1/23/2013
 Label each supplementary,
complementary, or neither.
 1. 40º + 50º
 2. 130º + 50º
 3. 45º + 35º
 4. 65º + 25º
 5. 123º + 62º
 6. 145º + 35º
 7. 12º + 108º
 8. 54º + 36º

3. Warm Up 1/23/2013
 Label each supplementary,
complementary, or neither.
 1. 40º + 50º 90º Complementary
 2. 130º + 50º 180º Straight
 3. 45º + 35º 80º Neither
 4. 65º + 25º 90º Complementary
 5. 123º + 62º 185º Neither
 6. 145º + 35º 180º Straight
 7. 12º + 108º 120º Neither
 8. 54º + 36º 90º Complementary

4. WARM UP 1/24/13
Identify the complement of each angle.
1. 15º 2. 36º 3. 89º 4. 76º

5. 1-5 Quiz
 Label your paper: Name/Date/Block/1-5 Quiz
Identify the complement of each angle.
1. 15º 2. 36º 3. 89º 4. 76º
5. 24º 6. 47º 7. 87º 8. 1º
Identify the supplement of each angle.
9. 63º 10. 101º 11. 56º 12. 28º
13. 34º 14. 15º 15. 154º 16. 89º
H
Find the missing G
F A
angles. <H
= 35, <E = 55, <G = 45, <B = 45 E B
C
17. A = ____ 18. C = ____ 19. D = ___ D
20. F = ____

6. Example 1
 The
measure of one of two
complementary angles is 20º. What is the
measure of the second angle?

7. Example 1
 The
measure of one of two
complementary angles is 20º. What is the
measure of the second angle?
 Step 1: Call the unknown angle measure
x.

8. Example 1
 The
measure of one of two
complementary angles is 20º. What is the
measure of the second angle?
 Step 1: Call the unknown angle measure
x.
 Step 2: 20º + x = 90º by definition of
complementary angles.

9. Example 1
 The
measure of one of two
complementary angles is 20º. What is the
measure of the second angle?
 Step 1: Call the unknown angle measure
x.
 Step 2: 20º + x = 90º by definition of
complementary angles.
 Step 3: x = 90º - 20º … X = 70º

10. Example 2
 The
measure of one of two
supplementary angles is 35º. W hat is the
measure of the second angle?

11. Example 2
 The measure of one of two
supplementary angles is 35º. W hat is the
measure of the second angle?
 Step 1: Call the unknown measure y.

12. Example 2
 The measure of one of two
supplementary angles is 35º. W hat is the
measure of the second angle?
 Step 1: Call the unknown measure y.
 Step 2: 35º + y = 180º by the definition of
supplementary angles

13. Example 2
 The measure of one of two
supplementary angles is 35º. W hat is the
measure of the second angle?
 Step 1: Call the unknown measure y.
 Step 2: 35º + y = 180º by the definition of
supplementary angles
 Step 3: y = 180º - 35º … y = 145º

14. Example 3
 The measure of one supplementary angle
is twice the measure of the second
supplementary angle. What is the
measure of each angle?

15. Example 3
 The measure of one supplementary angle
is twice the measure of the second
supplementary angle. What is the
measure of each angle?
 Step 1: Let w be the measure of the
smaller angle. Let 2w be the measure of
the larger angle.

16. Example 3
 The measure of one supplementary angle is twice the
measure of the second supplementary angle. What
is the measure of each angle?
 Step 1: Let w be the measure of the smaller angle.
Let 2w be the measure of the larger angle.
 Step 2: 2w + w = 180º by the definition of
supplementary angles.

17. Example 3
 The measure of one supplementary angle is twice the
measure of the second supplementary angle. What
is the measure of each angle?
 Step 1: Let w be the measure of the smaller angle.
Let 2w be the measure of the larger angle.
 Step 2: 2w + w = 180º by the definition of
supplementary angles.
 Step 3: 3w = 180º …. w = 60º
x W = 60º
z y

18. Example 3
 The measure of one supplementary angle is twice the
measure of the second supplementary angle. What
is the measure of each angle?
 Step 1: Let w be the measure of the smaller angle.
Let 2w be the measure of the larger angle.
 Step 2: 2w + w = 180º by the definition of
supplementary angles.
 Step 3: 3w = 180º …. w = 60º
 Step 4: x + 60º = 180º x W = 60º
 X = 180º - 60º z y
X = 120º so m<x = 120º

19. Example 3
 The measure of one supplementary angle is twice the
measure of the second supplementary angle. What
is the measure of each angle?
 Step 1: Let w be the measure of the smaller angle.
Let 2w be the measure of the larger angle.
 Step 2: 2w + w = 180º by the definition of
supplementary angles.
 Step 3: 3w = 180º …. w = 60º
 Step 4: x + 160º = 180º X =120 W = 60º
 X = 180º - 60º z Y
X = 120º so m<x = 120º
 Step 5: y + 60º = 180º
 Y = 180º - 60º
 Y = 120º so m<y = 120º

20. Example 3
 The measure of one supplementary angle is twice the
measure of the second supplementary angle. What is the
measure of each angle?
 Step 1: Let w be the measure of the smaller angle. Let 2w
be the measure of the larger angle.
 Step 2: 2w + w = 180º by the definition of supplementary
angles.
 Step 3: 3w = 180º …. w = 60º
 Step 4: x + 160º = 180º
 X = 180º - 60º
 X = 120º so m<x = 120º
 Step 5: y + 60º = 180º X =120 W = 60º
 Y = 180º - 60º
z
 Y = 120º so m<y = 120º Y = 120º
 Step 6: z + 120º = 180º
 Z = 180º - 120º
 Z = 60º

21. Example 3
 The measure of one supplementary angle is twice the
measure of the second supplementary angle. What is the
measure of each angle?
 Step 1: Let w be the measure of the smaller angle. Let 2w
be the measure of the larger angle.
 Step 2: 2w + w = 180º by the definition of supplementary
angles.
 Step 3: 3w = 180º …. w = 60º
 Step 4: x + 160º = 180º
 X = 180º - 60º
 X = 120º so m<x = 120º
 Step 5: y + 60º = 180º X =120 W = 60º
 Y = 180º - 60º
 Y = 120º so m<y = 120º Z = 60º Y = 120º
 Step 6: z + 120º = 180º
 Z = 180º - 120º
 Z = 60º

22. Think-Pair-Share
 Complete the problem that matches the
color of post it that you received…
Complete on loose leaf…
 Pink: The measure of one of two
complementary angles equals 30º. What is
the measure of the second angle?
 Blue: The measure of one of two
supplementary angles equals 30º. What is
the measure of the second angle?
 Orange: The measure of one of two
supplementary angles is 3 times larger than
the other. What are the measures of the
angles?

23. Think-Pair-Share
 Complete the problem that matches the color of
post it that you received… Complete on loose
leaf…
 Pink: The measure of one of two complementary
angles equals 30º. What is the measure of the
second angle?
 Blue: The measure of one of two supplementary
angles equals 30º. What is the measure of the
second angle?
 Orange: The measure of one of two
supplementary angles is 3 times larger than the
other. What are the measures of the angles?
 **Now – Find the person with the matching post
it. Compare your answers and determine a
method for teaching the class your problem**

24. Independent Assignment
 30Minutes
 Pages 26-27 All

25. Closure
 Homework: Workbook Activity 7
 Parking Lot Post It
 Tomorrow: Review
 Friday: Chapter 1 Test