1. Point A location Line Line segment Ray A straight path that goes on forever in both directions. A straight path between the points, called its endpoints. A straight path that goes on forever in one direction from an endpoint. Geometry Terms End Point

2. If we look around us, we will see angles everywhere. Angles In Daily Life

3. To name an angle, we name any point on one ray, then the vertex, and then any point on the other ray. For example:  ABC or  CBA We may also name this angle only by the single letter of the vertex, for example  B. A B C Review Naming an Angle

4. There are four main types of angles. Straight angle Right angle Acute angle Obtuse angle A B C A B C A B C BA C Review Types f Angles

5. Right angle: An angle whose measure is 90 degrees. Right AngleAcute AngleStraight AngleObtuse Angle

6. Examples Of Right Angle

7. Examples Of Obtuse Angle

8. Acute angle: An angle whose measure is less than 90 degrees. Right AngleAcute AngleStraight AngleObtuse Angle

9. Examples Of Acute Angle

10. Straight angle: An angle whose measure is 180 degrees. Right AngleAcute AngleStraight AngleObtuse Angle

11. Examples Of Straight Angle

12. Lines in a plane What can you say about these pairs of lines? These lines cross, or intersect. These lines do not intersect. They are parallel.

13. Angles Angles are measured in degrees. A quarter turn measures 90°. It is called a right angle. We label a right angle with a small square called a square corner. 90°

14. Angles A half turn measures 180°. This is a straight angle 180°

15. Angles A full turn measures 360°. 360°

16. Adjacent Angles Two angles that have a common vertex and a common ray are called adjacent angles. “SIDE BY SIDE” C D B A Common ray Common vertex Adjacent Angles  ABD and  DBC Adjacent angles do not overlap each other. D E F A B C  ABC and  DEF are not adjacent angles

17. More examples of adjacent angles. 55º 35º 50º130º 80º 45º 85º 20º

18. Missing Angles Our learning objectives today To calculate missing angles on a straight line, around a point and in a triangle.

19. What do you need to know? Angles in a triangle add up to................. 180° Angles on a straight line add up to....... 180° Angles around a point add up to............. 360°

20. Complementary Angles Two angles are called complementary angles if the sum of their degree measurements equals 90 degrees. Example: These two angles are complementary.

21. These two angles can be “put" together to form a right angle which is complementary!

22. Supplementary Angles Two angles are called supplementary angles if the sum of their degree measurements equals 180 degrees. Example: These two angles are supplementary.

23. These two angles can be “put" together to form a straight line!

24. Find the missing angle. You do not have a protractor. Use the clues in the pictures. 1. x 55 X=35

25. Find the missing angle. You do not have a protractor. Use the clues in the pictures. 2. 165 x X=15

26. Calculate the missing straight line angle 69 ° 111 °

27. Calculate the missing triangle angle 54° 89 ° 37°

28. Calculate the missing straight line angle 42° 103 ° 35°