1. Measure and classify angles.
Identify and use congruent angles and the bisector of an angle.
Splash Screen

2. Mathematical Practices 5 Use appropriate tools strategically.
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.).
Mathematical Practices
5 Use appropriate tools strategically.
6 Attend to precision.
CCSS

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

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

5. 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

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

7. Angles and Their Parts C.
Example 1

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

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. 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

15. 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

16. 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

17. 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

18. 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

19. Homework
Page 41 (12-36) / Page 42 (37-42)
CCSS