Students learn to measure and classify angles.

1. You will learn to measure, draw, and classify angles. What You'll Learn 1) Degrees 2) Protractor 3) Right Angle 4) Acute Angle 5) Obtuse Angle Angle Measure Vocabulary

2. In geometry, angles are measured in units called _______. degrees Angle Measure

3. In geometry, angles are measured in units called _______. degrees The symbol for degree is ° . Angle Measure

4. In geometry, angles are measured in units called _______. degrees The symbol for degree is ° . In the figure to the right, the angle is 75 degrees. In notation , there is no degree symbol with 75 because the measure of an angle is a real number with no unit of measure. Angle Measure Q P R 75 ° m PQR = 75

5. Angle Measure For every angle, there is a unique positive number between __ and ____ called the degree measure of the angle. Postulate 3-1 Angles Measure Postulate B A C n °

6. 0 Angle Measure For every angle, there is a unique positive number between __ and ____ called the degree measure of the angle. Postulate 3-1 Angles Measure Postulate B A C n °

7. 0 180 Angle Measure For every angle, there is a unique positive number between __ and ____ called the degree measure of the angle. Postulate 3-1 Angles Measure Postulate B A C n °

8. 0 180 Angle Measure For every angle, there is a unique positive number between __ and ____ called the degree measure of the angle. Postulate 3-1 Angles Measure Postulate B A C n ° m ABC = n and 0 < n < 180

9. Find the measurement of: Angle Measure J H G S Q R m SRQ = m S RJ = m SRG = m QRG = m GRJ = m SRH

10. Find the measurement of: 180 45 150 70 180 – 150 = 30 150 – 45 = 105 Angle Measure J H G S Q R m SRQ = m S RJ = m SRG = m QRG = m GRJ = m SRH

11. Use a protractor to draw an angle having a measure of 135. Angle Measure

12. Use a protractor to draw an angle having a measure of 135. Angle Measure 1) Draw AB A B

13. Use a protractor to draw an angle having a measure of 135. 2) Place the center point of the protractor on A. Align the mark labeled 0 with the ray. Angle Measure 1) Draw AB A B

14. Use a protractor to draw an angle having a measure of 135. 2) Place the center point of the protractor on A. Align the mark labeled 0 with the ray. Angle Measure 1) Draw AB 3) Locate and draw point C at the mark labeled 135. Draw AC. A B

15. Use a protractor to draw an angle having a measure of 135. 2) Place the center point of the protractor on A. Align the mark labeled 0 with the ray. Angle Measure 1) Draw AB 3) Locate and draw point C at the mark labeled 135. Draw AC. C A B

16. Once the measure of an angle is known, the angle can be classified as one of three types of angles. These types are defined in relation to a right angle. Angle Measure

17. Once the measure of an angle is known, the angle can be classified as one of three types of angles. These types are defined in relation to a right angle. Angle Measure Types of Angles A

18. Once the measure of an angle is known, the angle can be classified as one of three types of angles. These types are defined in relation to a right angle. Angle Measure Types of Angles obtuse angle 90 < m A < 180 A

19. Once the measure of an angle is known, the angle can be classified as one of three types of angles. These types are defined in relation to a right angle. Angle Measure Types of Angles A obtuse angle 90 < m A < 180 A

20. Once the measure of an angle is known, the angle can be classified as one of three types of angles. These types are defined in relation to a right angle. Angle Measure Types of Angles A right angle m A = 90 obtuse angle 90 < m A < 180 A

21. Once the measure of an angle is known, the angle can be classified as one of three types of angles. These types are defined in relation to a right angle. Angle Measure Types of Angles A right angle m A = 90 A obtuse angle 90 < m A < 180 A

22. Once the measure of an angle is known, the angle can be classified as one of three types of angles. These types are defined in relation to a right angle. Angle Measure Types of Angles A right angle m A = 90 acute angle 0 < m A < 90 A obtuse angle 90 < m A < 180 A

23. Classify each angle as acute , obtuse , or right . Angle Measure 110 ° 90 ° 40 ° 50 ° 130 ° 75 °

24. Classify each angle as acute , obtuse , or right . Obtuse Obtuse Acute Acute Acute Right Angle Measure 110 ° 90 ° 40 ° 50 ° 130 ° 75 °

25. Angle Measure 5x - 7 B The measure of B is 138. Solve for x.

26. Given: (What do you know?) Angle Measure 5x - 7 B The measure of B is 138. Solve for x. B = 5x – 7 and B = 138

27. Given: (What do you know?) 5x – 7 = 138 5x = 145 x = 29 Angle Measure 5x - 7 B The measure of B is 138. Solve for x. B = 5x – 7 and B = 138

28. Given: (What do you know?) 5x – 7 = 138 5x = 145 x = 29 5(29) -7 = ? 145 -7 = ? 138 = 138 Check! Angle Measure 5x - 7 B The measure of B is 138. Solve for x. B = 5x – 7 and B = 138

29. Angle Measure 9y + 4 H The measure of H is 67. Solve for y.

30. Given: (What do you know?) Angle Measure 9y + 4 H The measure of H is 67. Solve for y. H = 9y + 4 and H = 67

31. Given: (What do you know?) 9y + 4 = 67 9y = 63 y = 7 Angle Measure 9y + 4 H The measure of H is 67. Solve for y. H = 9y + 4 and H = 67

32. Given: (What do you know?) 9y + 4 = 67 9y = 63 y = 7 9(7) + 4 = ? 63 + 4 = ? 67 = 67 Check! Angle Measure 9y + 4 H The measure of H is 67. Solve for y. H = 9y + 4 and H = 67

33. Angle Measure End of Lesson