1. Geometric Relationships 5-1 Angle Relationships

2. Angle Review: What kind of angle is this? Right Angle 90⁰

3. Naming Angles Angles may be named by the vertex letter name Angle B Angles may be named using numbers Angle 1 Angles may be named using the vertex and points on each ray (vertex MUST be middle letter!) Angle ABC or Angle CBA A B 1 C

4. What kind of angle do the hands of a clock make at: 5:00? greater than 90⁰ obtuse 10:00? less than 90⁰ acute 3:00? exactly 90⁰ right

5. What kind of angle do the hands of a clock make at: 5:00? greater than 90⁰ obtuse 10:00? less than 90⁰ acute 3:00? exactly 90⁰ right 1:30? less than 90⁰ acute 8:30? greater than 90⁰ obtuse 6:00? greater than 90⁰ straight

6. Classifying Angles – Use the diagram to identify: C D 90⁰ 30⁰ 60⁰ A E B Two acute angles: 1) Angle AED or DEA 2) Angle CEB or BEC

7. Classifying Angles – Use the diagram to identify: C D 90⁰ 30⁰ 60⁰ A E B Two obtuse angles: 1) Angle AEC or CEA 2) Angle DEB or BED

8. Classifying Angles – Use the diagram to identify: C D 90⁰ 30⁰ 60⁰ A E B A pair of complementary angles: Angle AED and angle CEB 30 + 60 = 90

9. Classifying Angles – Use the diagram to identify: C D 90⁰ 30⁰ 60⁰ A E B Two pairs of supplementary angles: 1) Angle AEC and angle CEB 120 + 60 = 180 2) Angle AED and angle DEB 30 + 150 = 180

10. Finding Angle Measures – Use the diagram to find each angle measure: 3 2 4 1 If m ⁄ 2 = 75⁰, find m ⁄ 3. m ⁄ 2 + m ⁄ 3 = 180 75 + m ⁄ 3 = 180 -75 m ⁄ 3 = 105⁰ They form a straight line, so they are supplementary, which means they add up to 180⁰.

11. Finding Angle Measures – Use the diagram to find each angle measure: 3 2 4 1 If m ⁄ 2 = 75⁰, find m ⁄ 4. ⁄ 2 and ⁄ 4 are vertical angles. m ⁄ 2 = 75⁰, so m ⁄ 4 = 75⁰ Vertical angles are congruent!

12. Art Application – An artist is designing a section of a stained glass window. Based on the diagram, what would be the measure of angle ECF? A B 32⁰ C D 32 E F 58⁰

13. Group Work Textbook page 198-199 (1-8)

14. Homework Textbook page 199 (9-16)