Classifying and Measuring Angles

A middle school math lesson on classifying and measuring angles

1. Classifying Angles Objectives: I can name angles in four different ways. I can classify angles as acute, right, obtuse, or straight. I can identify vertical and adjacent angles. I can find missing measures of angles

2. Angles A shape formed by two rays sharing a common endpoint; contains two rays and a vertex ray ray vertex vertex —point common to two rays of a triangle or two sides of a polygon ray —has one endpoint and goes infinitely in one direction

3. How are angles used in real life? Sports The Arts

4. How are angles used in real life? Transportation Architecture & Engineering

5. Naming Angles There are 4 ways to name an angle: Using the vertex Example: < O Using the number Example: < 1 Using the points with the vertex in the middle Example: < MOP or < POM

6. Name that angle… Using the vertex Using the number Using the points with the vertex in the middle

7. There are 4 basic types of angles: Acute Right Obtuse Straight

8. acute Angle An acute angle measures less than 90° and looks like this: It measures more than 0 degrees but less than 90 degrees. 0 < acute angle < 90

9. acute Angles measures less than 90°

10. Which angles are not acute? 1 2 3 4 5

11. Right Angles A right angle measures exactly 90° and looks like this: We draw the square around the right angle so we quickly identify it as a 90° angle. These angles are the most common in everyday life: the corner of a door, window, table, piece of paper .

12. Right Angles measures exactly 90°

13. Which angle is a right angle? 1 2 3 4 5

14. DON’T FORGET this about me…….

15. obtuse Angle An obtuse angle measures more than 90° and looks like this: It measures more than 90 degrees but less than 180 degrees . 90 < obtuse angle < 180

16. obtuse Angles measures more than 90°

17. Which angle is obtuse? 1 2 3 4 5

18. straight Angle A straight angle measures exactly 180° and looks like this: It makes a straight line.

19. straight Angles measures exactly 180°

20. Which angle is a straight angle? 1 2 3 4 5 6

21. Just a little jokey-joke for you:

22. adjacent Angles NEXT DOOR NEIGHBOR Adjacent angles are “side by side” and share a common ray and vertex.

23. These are examples of adjacent angles. 55 º 35 º 50 º 130 º 80 º 45 º 85 º 20 º

24. These angles are NOT adjacent. 45 º 55 º 50 º 100 º 35 º 35 º

25. VERTICAL Angles OPPOSITES When 2 lines intersect, they make vertical angles. Vertical angles are opposite one another. 75 º 75 º 105 º 105 º

26. Vertical angles are congruent (equal). 30 º 150 º 150 º 30 º

27. Finding the value of a missing measure using what we know about vertical angles… Find the value of x in the figure below. YOU TRY!_____________________________ What is the value of x in the figure below?

28. Practice time! LET’S PLAY A GAME CALLED…. WHAT’S YOUR ANGLE?

29. Exit slip Show me what you learned today! Complete the Exit Slip and turn it in to tray 1 on your way out when I dismiss you. DON’T FORGET TO DO YOUR HOMEWORK & COMPLETE HOMEWORK LOG