1. What’s Your Angle?

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 Congruent angles: two angles that have equal measures.
Ray: part of a line that has an endpoint and extends forever.
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°
45°

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

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

11. 1. 2. 3. 4. 5. 6. 7. 8.

12. Alternate Interior Angles1. 2. 3. 4. 5. 6. 7. 8.
Angle 3 and Angle 6 are congruent angles. This means they have the same measure.

13. Alternate Interior Angles1. 2. 3. 4. 5. 6. 7. 8.
Angle 4 and Angle 5 are congruent angles.

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

15. Vertical Angles Angle 1 and Angle 4 are congruent angles. 1. 2. 3. 4.5. 6. 7. 8.
Angle 1 and Angle 4 are congruent angles.

16. Vertical Angles Angle 2 and Angle 3 are congruent angles. 1. 2. 3. 4.5. 6. 7. 8.
Angle 2 and Angle 3 are congruent angles.

17. Vertical Angles Angle 5 and Angle 8 are congruent angles. 1. 2. 3. 4.5. 6. 7. 8.
Angle 5 and Angle 8 are congruent angles.

18. Vertical Angles Angle 6 and Angle 7 are congruent angles. 1. 2. 3. 4.5. 6. 7. 8.
Angle 6 and Angle 7 are congruent angles.

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

20. Corresponding Angles Angle 1 and Angle 5 are congruent angles. 1. 2.3. 4. 5. 6. 7. 8.
Angle 1 and Angle 5 are congruent angles.

21. Corresponding Angles Angle 2 and Angle 6 are congruent angles. 1. 2.3. 4. 5. 6. 7. 8.
Angle 2 and Angle 6 are congruent angles.

22. Corresponding Angles Angle 3 and Angle 7 are congruent angles. 1. 2.3. 4. 5. 6. 7. 8.
Angle 3 and Angle 7 are congruent angles.

23. Corresponding Angles Angle 4 and Angle 8 are congruent angles. 1. 2.3. 4. 5. 6. 7. 8.
Angle 4 and Angle 8 are congruent angles.

24. 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!

25. WHY?? Angle 2 measures 110°. What do the other angles measure? 1. 2.3. 4. 5. 6. 7. 8.
WHY??