1. Splash Screen

2. Then/Now You measured line segments. (Lesson 1–2) Measure and classify angles. Identify and use congruent angles and the bisector of an angle.

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

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

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

6. Example 1 Angles and Their Parts C.

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

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

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

10. Concept

11. Example 2 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.

12. Example 2 Measure and Classify Angles

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

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

15. Example 3 Measure and Classify Angles  GBH   HCIGiven m  GBH  m  HCIDefinition of congruent angles 2x + 5= 3x – 10Substitution 2x + 15= 3xAdd 10 to each side. 15= xSubtract 2x from each side. Step 1 Solve for x.

16. Example 3 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

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