1. Section 1-4 Angles and their Measures

2. Angle Formed by two rays with a common endpoint –T–The rays are the sides of the angle –T–The common endpoint is called the vertex of the angle.

3. X Y W Name the sides of the Angle. and Name the vertex of the angle. W

4. When naming an angle, the vertex must be in the middle when using 3 points.

5. An angle can be named by its vertex only if it names one angle!

6. For Example: X Y W

7. D A V E You cannot name this angle by its vertex because it names 3 angles!

8. Protractor Tool that measures angles –m–measured in degrees

9. Angles that have the same measure are called congruent angles.

10. Measures are equal! Angles are congruent! For example:

11. An angle separates a plane in 3 distinct parts: 1.Interior of the angle. 2.Exterior of the angle. 3.Angle itself.

12. A point is in the interior of an angle if it is between points that lie on each side of the angle. A point is in the exterior of an angle if it is not on the angle or in its interior.

13. X Y W Z V Interior Exterior

14. Angle Addition postulate If P is in the interior of, then P S T R

15. Classifying Angles

16. Types of angles 1.Right Angle: measure equals 90 degrees 2.Acute Angle: measure is greater than 0 degrees and less than 90 degrees

17. Types of angles: 3.Obtuse Angle: the measure is greater than 90 degrees but less than 180 degrees 4.Straight Angle: measure equals 180 degrees

18. Classify each angle. Straight Angle Obtuse Angle Right Angle Acute Angle

19. Adjacent angles: Two angles that have a common vertex and a common side, but have no common interior points.