1. Lesson 11.1 Angle and Line Relationships

2. Vertical Angles
- Opposite angles that are formed by intersecting lines. a
Opposite angles (vertical angles)
are ALWAYS congruent. b

3. Adjacent Angles
Share a vertex and a side but no points in the interiors.
<AXB and <BXC are adjacent angles B A
<AXC and <BXC are not adjacent angles
Why? X C

4. Complementary Angles
- Angles whose
sum is 90 . a b
Complementary
angles do not
have to be
adjacent. x y

5. Supplementary Angles
- Angles whose
sum is 180 . k t
Supplementary
angles do not
have to be
adjacent. b c

6. Find the value of n. 1) 2)

7. Congruent Angles
Angles that have the same measurement
Notation:

8. Lines

9. Identifying Corresponding Angles
Transversal
-A line that intersects two other lines.

10. Identifying Corresponding Angles
- Two angles that are formed by two lines and a transversal and occupy corresponding positions. A B 1 2 3 4 5 6 C 7 8 D
Corresponding Angles
If the two lines are parallel, then the corresponding angles are congruent.

11. Identifying Alternate Interior Angles
-interior of a pair of lines on opposite sides of the transversal. A B 1 2 3 4 5 6 C 7 8 D
Corresponding Angles
If the two lines are parallel, then the alternate interior angles are congruent.

12. Identifying Alternate Exterior Angles
-on opposite sides of the transversal and outside the parallel lines A B 1 2 3 4 5 6 C 7 8 D
Corresponding Angles
If the two lines are parallel, then the alternate exterior angles are congruent.

13. Homework
11.1 worksheet