1. What’s Your Angle? By Kim Davis

2. Background Vocabulary Plane: an infinite, flat surface. Parallel lines: lines in a plane that never meet. l l is the symbol for parallel lines. Transversals: lines that intersect two or more parallel lines.

3. More Vocabulary 1.Congruent angles: two angles that have equal measures. 2.Ray: part of a line that has an endpoint and extends forever. 3.Angles: two rays with a common endpoint.

4. Types of Angles Acute : angles that measure less that 90°.

5. Right: angles that measure 90°.

6. Obtuse: angles that measure more than 90° and less than 180°

7. Straight: angles that measure 180°.

8. Complementary Angle Two angles whose measure add up to 90°. 45°

9. Supplementary Angles Two angles whose measures add up to 180°. Supplementary Angles Two angles whose measures add up to 180°. 90°

10. Congruent Angles When a transversal intersects two parallel lines, eight angles are formed.

11. 2.1. 3.4. 5.6. 7.8.

12. 2.1. 3.4. 5.6. 7.8. Alternate Interior Angles Angle 3 and Angle 6 are congruent angles. This means they have the same measure.

13. 2.1. 3.4. 5.6. 7.8. Alternate Interior Angles Angle 4 and Angle 5 are congruent angles.

14. The measure of angle 4 and the measure of angle 6 are congruent AND The measure of angle 3 and the measure of angle 5 are congruent.

15. NOTE Alternate Interior Angles are on “alternate” sides and on the “interior” of the parallel lines.

16. 2.1. 3.4. 5.6. 7.8. Vertical Angles Angle 1 and Angle 4 are congruent angles.

17. 2.1. 3.4. 5.6. 7.8. Vertical Angles Angle 2 and Angle 3 are congruent angles.

18. 2.1. 3.4. 5.6. 7.8. Vertical Angles Angle 5 and Angle 8 are congruent angles.

19. 2.1. 3.4. 5.6. 7.8. Vertical Angles Angle 6 and Angle 7 are congruent angles.

20. The measures of Angle 1 and Angle 3 are congruent. The measures of Angle 2 and Angle 4 are congruent. The measures of Angle 5 and Angle 7 are congruent. The measures of Angle 6 and Angle 8 are congruent.

21. NOTE Vertical Angles are diagonally across from each other.

22. Corresponding Angles These angles are a bit trickier. You have to imagine cutting your diagram apart, and then pasting one part on top of the other.

23. 2.1. 3.4. 5.6. 7.8. Corresponding Angles Angle 1 and Angle 5 are congruent angels.

24. 2.1. 3.4. 5.6. 7.8. Corresponding Angles Angle 2 and Angle 6 are congruent.

25. 2.1. 3.4. 5.6. 7.8. Corresponding Angles Angle 3 and Angle 7 are congruent angles.

26. 2.1. 3.4. 5.6. 7.8. Corresponding Angles Angle 4 and Angle 8 are congruent angles.

27. Angle 1 and Angle 5 are congruent. Angle 2 and Angle 6 are congruent. Angle 3 and Angle 7 are congruent. Angle 4 and Angle 8 are congruent.

28. Demonstrate Your Knowledge Now that you’ve seen what is congruent, you can take the measurement of “1” angle and figure out the others. Let’s try it!

29. 2.1. 3.4. 5.6. 7.8. Angle 2 measures 110°. What do the other angles measure?