1. Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes

2. Warm Up Solve. 1. x + 30 = 90 2. 103 + x = 180 x = 60 3. 32 + x = 180

3. Problem of the Day
Mrs. Meyer’s class is having a pizza party. Half the class wants pepperoni on the pizza, of the class wants sausage on the pizza, and the rest want only cheese on the pizza. What fraction of Mrs. Meyer’s class wants just cheese on the pizza? 1 3 1 6

4. Sunshine State Standards
MA.8.G.2.2 Classify and determine the measure of angles,…

5. Vocabulary angle adjacent angles right angle supplementary angles
acute angle complementary angles
obtuse angle
straight angle
vertical angles
congruent angles

6. An angle () is formed by two rays, or sides, with a common endpoint called the vertex. You can name an angle several ways: by its vertex, by its vertex and a point on each ray, or by a number. When three points are used, the middle point must be the vertex.

8. Additional Example 1: Classifying Angles
Use the diagram to name each figure.
A. two acute angles
TQP, RQS
mTQP = 43°; mRQS = 47°
B. two obtuse angles
SQP, RQT
mSQP= 133°; mRQT = 137°

9. Additional Example 1: Classifying Angles
Use the diagram to name each figure.
C. a pair of complementary angles
TQP, RQS
mTQP + mRQS = 43° + 47° = 90
B. two pairs of supplementary angles
TQP, TQR
mTQP + mTQR = 43° + 137° = 180
SQP, SQR
mSQP + mSQR = 133° + 47° = 180

10. Check It Out: Example 1
Use the diagram to name each figure.
A. two acute angles
AEB measures 58° and DEC measures 58°
B. two obtuse angles
AEC measures 148° and DEB measures 122°

11. Check It Out: Example 1
Use the diagram to name each figure.
C. a pair of complementary angles
AEB measures 58° and DEC measures 32° = 90°
D. a pair of supplementary angles
AEC measures 148° and DEC measures 32° = 180°; AEB measures 58° and DEB measures 122°, = 180°

12. Additional Example 2A: Finding Angle Measures
Use the diagram to find each angle measure.
If m1 = 37°, find m2.
m1 + m2 = 180°
1 and 2 are supplementary.
37° + m2= 180°
Substitute 37 for m1.
–37° –37°
Subtract 37 from both sides.
m2 = 143°

13. Additional Example 2B: Finding Angle Measures
Use the diagram to find each angle measure.
Find m3 = 37°.
m2 + m3 = 180°
2 and 3 are supplementary.
143° + m3 = 180°
Substitute 143 for m2.
–143° –143°
Subtract 143 from both sides.
m3 = 37°

14. Use the diagram to find each angle measure.
Check It Out: Example 2A
Use the diagram to find each angle measure.
If m3 = 142°, find m4.
m3 + m4 = 180°
142° + m4= 180°
–142° –142°
m4 = 38°

15. Use the diagram to find each angle measure.
Check It Out: Example 2B
Use the diagram to find each angle measure.
Find m1.
m1 + m4 = 180°
m ° = 180°
m = 142°
–38° –38°

16. Adjacent angles have a common vertex and a common side, but no common interior points. Angles 1 and 2 in the diagram are adjacent angles.
Congruent angles have the same measure.
Vertical angles are the nonadjacent angles formed by two intersecting lines. Angles 2 and 4 are vertical angles. Vertical angles are congruent.

17. Additional Example 3: Application
A traffic engineer designed a section of roadway where three streets intersect. Based on the diagram, what is the measure of DBE.
Step 1: Find mCBD.
ABF  CBD
Vertical angles are congruent.
Congruent angles have the same measure.
mABF = mCBD
mCBD = 26
Substitute 26 for mCBD.

18. Additional Example 3 Continued
A traffic engineer designed a section of roadway where three streets intersect. Based on the diagram, what is the measure of DBE.
Step 2: Find mDBE.
mCBD + mDEB = 90°
The angles are complementary.
26 + mDEB = 90°
Substitute 26 for mCBD.
–26° –26°
Subtract 26 from both sides.
mDEB = 64°

19. Based on the map, what is the measure of BGC?
Check It Out: Example 3
Based on the map, what is the measure of BGC?
AGB is congruent to EGF. mAGB = 42°
mBGC + mAGB = 90°
mBGC + 42° = 90°
mBGC = 48°

20. Lesson Quiz for Student Response Systems
Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems 20

21. Lesson Quiz
Use the diagram to name each figure or find each angle measure.
1. a right angle
Possible answer: CGD
2. two acute angles
Possible answer: 1, 2
3. pair of complementary angles
Possible answer: 3, 4
4. If m1 = 47°, then find m 3.
47°
5. Find m4.
43°

22. Lesson Quiz for Student Response Systems
1. If m1 = 42°, then find m 3.
A. 3°
B. 42°
C. 48°
D. 90° 22

23. Lesson Quiz for Student Response Systems
2. Name a pair of complementary angles.
A. CGD
B. AGF
C. AGB, BGC
D. CGD, DGF 23

24. Lesson Quiz for Student Response Systems
3. Find mCGD.
A. 3°
B. 42°
C. 90°
D. 180° 24