1. LESSON 1–4
Angle Measure

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

3. A. Name all angles that have B as a vertex.
Angles and Their Parts
A. Name all angles that have B as a vertex.
Answer:
Example 1

4. Angles and Their Parts
B. Name the sides of 5.
Answer:
Example 1

5. Angles and Their Parts C.
Example 1

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

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

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

9. Concept

10. A. Measure TYV and classify it as right, acute, or obtuse.
Measure and Classify Angles
A. Measure TYV and classify it as right, acute, or obtuse.
Answer: mTYV = 90, so TYV is a right angle.
Example 2

11. Answer: 180 > mWYT > 90, so WYT is an obtuse angle.
Measure and Classify Angles
Answer: 180 > mWYT > 90, so WYT is an obtuse angle.
Example 2

12. Measure and Classify Angles
Example 2

13. 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

14. 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

15. 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

16. Measure and Classify Angles
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

17. mGBH = mHCI Definition of congruent angles
Measure and Classify Angles
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

18. Step 2 Use the value of x to find the measure of either angle.
Measure and Classify Angles
Step 2 Use the value of x to find the measure of either angle. .
Answer: mGBH = 35, mHCI = 35
Example 3

19. 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

20. LESSON 1–4
Angle Measure