1. Special Pairs of Angles Return to table of contents

2. Congruent Angles have the same angle measurement.

3. Complementary Angles are two angles with a sum of 90 degrees. These two angles are complementary angles because their sum is 90. Notice that they form a right angle when placed together.

4. Complementary Angles are two angles with a sum of 90 degrees. These two angles are complementary angles because their sum is 90. Although they aren't placed together, they can still be complementary.

5. Supplementary Angles are two angles with a sum of 180 degrees. These two angles are supplementary angles because their sum is 180. Notice that they form a straight angle when placed together.

6. Supplementary Angles are two angles with a sum of 180 degrees. These two angles are supplementary angles because their sum is 180. Although they aren't placed together, they can still be supplementary.

7. Vertical Angles are two angles that are opposite each other when two lines intersect. a b c d In this example, the vertical angles are: Vertical angles have the same measurement. So:

8. Using what you know about vertical angles, find the measure of the missing angles. b c a By Vertical Angles: By Supplementary Angles:

9. Adjacent Angles are two angles that are next to each other and have a common ray between them. This means that they are on the same plane and they share no internal points. A B C D  ABC is adjacent to  CBD How do you know? ·They have a common side (ray CB) ·They have a common vertex (point B)

10. Adjacent or Not Adjacent? You Decide! a b a b a b AdjacentNot Adjacent click to reveal

11. Alternate Exterior Angles are on opposite sides of the transversal and on the outside of the given lines. a b c d e f gh In this diagram the alternate exterior angles are: l m n Which line is the transversal?

12. Alternate Interior Angles are on opposite sides of the transversal and on the inside of the given lines. a b c d e f gh In this diagram the alternate interior angles are: m n l

13. Same Side Interior Angles are on same sides of the transversal and on the inside of the given lines. a b c d e f gh In this diagram the same side interior angles are: m n l

14. Special Case!!! If parallel lines are cut by a transversal then: ·Corresponding Angles are congruent ·Alternate Interior Angles are congruent ·Alternate Exterior Angles are congruent SO: 1 3 5 7 24 6 8 l m n