2. Example 1: Naming Angles Key Concept: Types of Angles
Main Idea
New Vocabulary
Example 1: Naming Angles
Key Concept: Types of Angles
Example 2: Classify Angles
Example 3: Classify Angles
Key Concept: Pairs of Angles
Example 4: Classify Angles
Example 5: Classify Angles
Example 6: Real-World Example
Lesson Menu

3. Classify and determine the measure of angles.
Main Idea/Vocabulary

4. angle vertex degrees right angle acute angle obtuse angle
straight angle
vertical angles
adjacent angles
complementary angles
supplementary angles
Main Idea/Vocabulary

5. Answer: The angle can be named in four ways: XYZ or ZYX, Y, or 1.
Naming Angles
Name the angle.
● Use the vertex as the middle letter and a point from each side. XYZ or ZYX
● Use the vertex only. Y
● Use a number. 1
Answer: The angle can be named in four ways: XYZ or ZYX, Y, or 1.
Example 1

6. Name the angle. A. ACB or BCA, C, or 2 B. CAB or CAB, A, or 2
C. ABC or CBA, B, or 2
D. CBC or CAB, B, or 2
Example 1 CYP

7. Key Concept 2

8. Classify the angle as acute, obtuse, right, or straight.
Classify Angles
Classify the angle as acute, obtuse, right, or straight.
Answer: The angle is between 90° and 180°, so it is an obtuse angle.
Example 2

9. Classify the angle as acute, obtuse, right, or straight.
A. acute
B. obtuse
C. right
D. straight
Example 2 CYP

10. Classify the following angle as acute, obtuse, right, or straight.
Classify Angles
Classify the following angle as acute, obtuse, right, or straight.
Answer: The angle is exactly 180°, so the angle is straight.
Example 3

11. Classify the following angle as acute, obtuse, right, or straight.
A. acute
B. obtuse
C. right
D. straight
Example 3 CYP

12. Key Concept 2

13. Classify Angles
Identify the following pair of angles as complementary, supplementary, or neither.
Answer: The sum of the two angles is 180°, so the angles are supplementary.
Example 4

14. Identify the following pair of angles as complementary, supplementary, or neither.
A. complementary
B. supplementary
C. neither
Example 4 CYP

15. Classify Angles
Identify the following pair of angles as complementary, supplementary, or neither.
Answer: The sum of the two angles is 140°, so they are neither complementary nor supplementary.
Example 5

16. Identify the following pair of angles as complementary, supplementary, or neither.
A. complementary
B. supplementary
C. neither
Example 5 CYP

17. TIME The hour, minute, and second hands make up two adjacent angles that form a right angle in the clock shown below. Find the missing angle.
Example 6

18. first angle second angle
Write an equation.
first angle second angle
x + 72 = 90
Solve the equation.
x + 72 = 90
Write the equation.
– 72 = – 72
Subtract 72 from each side.
x = 18
Simplify.
Answer: So, the value of x is 18.
Example 6

19. TIES The two adjacent angles in the ties form a right angle
TIES The two adjacent angles in the ties form a right angle. Find the missing angle measure.
A. 45°
B. 90°
C. 135°
D. 145°
Example 6 CYP