1. Five-Minute Check (over Lesson 1–3) Mathematical Practices Then/Now
New Vocabulary
Example 1: Real-World Example: Angles and Their Parts
Key Concept: Classify Angles
Example 2: Measure and Classify Angles
Example 3: Find the Angle Measure
Lesson Menu

2. Use the number line to find the measure of AC.
5-Minute Check 1

3. Use the number line to find the measure of DE.
C. 7
D. 9
5-Minute Check 2

4. Use the number line to find the midpoint of EG.
A. D
B. E
C. F
D. H
5-Minute Check 3

5. Find the distance between P(–2, 5) and Q(4, –3).
5-Minute Check 4

6. Find the coordinates of R if M(–4, 5) is the midpoint of RS and S has coordinates (0, –10).
B. (–4, 15)
C. (–2, –5)
D. (2, 20)
5-Minute Check 5

7. A boat located at (4, 1) can dock at two locations
A boat located at (4, 1) can dock at two locations. Location A is at (–2, 9) and Location B is at (9, –11). Which location is closest? How many units away is the closest dock?
A. Location A, 10 units
B. Location A, 12.5 units
C. Location B, 10 units
D. Location B, 12.5 units
5-Minute Check 6

8. Mathematical Practices 5 Use appropriate tools strategically.
6 Attend to precision.
Content Standards
G.CO.1 Know precise definitions of angle, circle, perpendicular line, parallel line, and line segment, based on the undefined notions of point, line, distance along a line, and distance around a circular arc.
G.CO.12 Make formal geometric constructions with a variety of tools and methods (compass and straightedge, string, reflective devices, paper folding, dynamic geometric software, etc.). MP

9. You measured line segments.
Measure and classify angles.
Identify and use congruent angles and the bisector of an angle.
Then/Now

10. ray degree right angle acute angle opposite rays angle obtuse angle
angle bisector
opposite rays
angle
side
vertex
interior
exterior
Vocabulary

11. A. Name all angles that have B as a vertex.
Angles and Their Parts
A. Name all angles that have B as a vertex.
Which angles have two noncollinear rays that meet at the same endpoint or vertex B?
Answer:
Example 1

12. Rays are the sides of the angles. What are the sides of ?
Angles and Their Parts
B. Name the sides of 5.
Rays are the sides of the angles. What are the sides of ?
Answer:
Example 1

13. Angles and Their Parts C.
When naming angles using three letters, the vertex must be the second of the three letters. You can name an angle using a single letter only when there is exactly one angle located at that vertex.
Use letters to name
Example 1

14. A. A. B. C. D.
Example 1a

15. B. A. B. C.
D. none of these
Example 1b

16. Which of the following is another name for 3?B. C. D.
Example 1c

17. Concept

18. A. Copy the diagram below, and extend each ray.
Measure and Classify Angles
A. Copy the diagram below, and extend each ray.
Classify each angle as right, acute, or obtuse.
Then use a protractor to measure the angle to the nearest degree.
Example 2

19. Measure and Classify Angles
Example 2

20. Measure and Classify Angles
Example 2

21. A. Measure CZD and classify it as right, acute, or obtuse.
A. 30°, acute
B. 30°, obtuse
C. 150°, acute
D. 150°, obtuse
Example 2a

22. B. Measure CZE and classify it as right, acute, or obtuse.
A. 60°, acute
B. 90°, acute
C. 90°, right
D. 90°, obtuse
Example 2b

23. C. Measure DZX and classify it as right, acute, or obtuse.
A. 30°, acute
B. 30°, obtuse
C. 150°, acute
D. 150°, obtuse
Example 2c

24. Find the Angle Measure
INTERIOR DESIGN Wall stickers of standard shapes are often used to provide a stimulating environment for a young child’s room. A five-pointed star sticker is shown with vertices labeled. Find mGBH and mHCI if GBH  HCI, mGBH = 2x + 5, and mHCI = 3x – 10.
Example 3

25. mGBH = mHCI Definition of congruent angles
Find the Angle Measure
Step 1 Solve for x.
GBH  HCI Given
mGBH = mHCI Definition of congruent angles
2x + 5 = 3x – 10 Substitution
2x + 15 = 3x Add 10 to each side.
15 = x Subtract 2x from each side.
Example 3

26. Step 2 Use the value of x to find the measure of either angle.
Find the Angle Measure
Step 2 Use the value of x to find the measure of either angle. .
Answer: mGBH = 35, mHCI = 35
Example 3

27. Find mBHC and mDJE if BHC  DJE, mBHC = 4x + 5, and mDJE = 3x + 30.
A. mBHC = 105, mDJE = 105
B. mBHC = 35, mDJE = 35
C. mBHC = 35, mDJE = 105
D. mBHC = 105, mDJE = 35
Example 3