1. Do Now 3/15/12 Take out HW from last night. Copy HW in your planner.
Text p. 312, #1-16 all, 21
Copy HW in your planner.
Text p. 318, #10-23 all, 27 & 28
In your journal, describe how to use a protractor. Use step-by-step instructions on how to measure an angle.

2. Homework Text p. 312, #1-16 all, 21 1) Q, R, S 2) 3) plane QRS 4) 5)6)
7) D, E, F 8)
9) plane DEF
10)
11)
12)
13) Plane ABC contains points A, B, C; lines AB & BC; line segments AB, AC, & BC; rays AB, BA, BC, CB, & CA. Plane ACD contains points A, C, D; line segments AC, AD, & CD; and ray CA

3. Homework Text p. 312, #1-16 all, 21
14) 6;
15) answer vary
16)
21) C

4. Objective
SWBAT identify angles and angle pairs

5. Section 8.2 “Classifying Angles”
two rays with a common endpoint. D
Sides C
Vertex E

6. Naming Angles The following angle can be named in three ways: B C A
Vertex

7. Types of Angles Right angle = 90 degrees
Acute angle = less than 90 degrees
Obtuse angle = more than 90 degrees
Straight angle = exactly 180 degrees

8. The MEASURE of is written as .
A PROTRACTOR can be used to approximate the measure of an angle.

9. Using a Protractor
Find
= 130° A C B

10. Using a Protractor
Find
= 70° A C B

11. What is the measure of a straight line (in degrees)?
180° A B C

12. Supplementary Angles 180° 150° 30°
When two angles form a straight line, the sum of their measures is 180° D
180°
150°
30° A C E

13. Complementary Angles 90° 64° 26°
When two angles form a right angle, the sum of their measures is 90° W
90°
64° Z
26° X Y

14. Use the diagram to tell whether the angles are complementary, supplementary, or neither.
OMP and PMQ O N P Q R M
30°
60°
OMP = 60° and PMQ = 30° and 30°+60° = 90° therefore, they are complementary.

15. Use the diagram to tell whether the angles are complementary, supplementary, or neither.
NMO and OMR O N P Q R M
165°
15°
NMO = 15° and OMR= 165° and 15°+165° = 180° therefore, they are supplementary.

16. Use the diagram to tell whether the angles are complementary, supplementary, or neither.
BAC and EAF C B D E F A
35°
35°
BAC = 35° and EAF= 35° and 35°+35° = 70° therefore, they are neither.

17. Finding Angle Measures
Angles A and B are complementary. If mA is 56°, what is the mB?
Since A and B are complementary, mA + mB = 90°.
mA + mB = 90°
56° + mB = 90°
Substitute 56° for mA.
– 56° – 56°
Subtract 56° from both sides.
mB = 34°
The measure of B = 34°.

18. Finding Angle Measures
Angles P and Q are supplementary. If mP is 32°, what is the mQ?
Since P and Q are supplementary, mP + mQ = 180°.
mP + mQ = 180°
32° + mQ = 180°
Substitute 32° for mP.
– 32° – 32°
Subtract 32° from both sides..
mQ = 148°
The measure of Q = 148°.

19. Homework
Text p. 318, #10-23 all, 27 & 28