1. Geometry1.2 Measurements of Segments and Angles

2. 1.2 Measurements of Segments and Angles A geometric object is distinct from its measure. Symbols are used carefully to distinguish between… Object Name Symbol Measure

3. Linear Units: meters (m), centimeters (cm), feet (ft), miles (mi) Angle Units: degrees ( )  Rule:

4. 4 Rulers

5. 5 A Protractor

6. Classifying Angles by their Measures Acute  Right  Obtuse  x° x < 90° x° x = 90° x° x > 90° Straight  x° x = 180°

7. Types of Angles Acute Angle: Measures between 0° and 90° Right Angle: Measure of 90° Obtuse Angle: Measure between 90° and 180° Straight Angle: Measure of 180°

8. Example Given that is a straight angle, find and

9. How many  s can you find? Name them. A B C D 1 2 3  s –  ADB or  BDA –  BDC or  CDB –  ADC or  CDA Notice D (the vertex) is always in the middle. Can’t use  D But  1 or  2 could be added.

10. Definition: Congruent Segments have equal length Definition: Congruent Angles have equal measure Congruence Symbol: Meaning: If then

11. Identify the line segments that are congruent in the figure. Using Marks to Identify Congruent Line Segments AB D C EF AB CD AC BD BF DF EC AE One tick mark Two tick marks Three tick marks Course 2 Building Bocks of Geometry

12. Using Marks to Identify Congruent Angles and Segments Name the Congruent Objects

14. Alternative Method for Measuring Angles DMS: Degrees, Minutes, Seconds 1 degree = 60 minutes 1 minute = 60 seconds