1. Do First

2. Complementary angles add up to 90º.
30º
40º
50º
60º
Adjacent and Complementary Angles
Complementary Angles but not Adjacent

3. Supplementary Angles sum to 180°
150°
30°

4. 2. Angle Relationships

5. 2. Angle Relationships Conjecture 2: Vertical Angles Conjecture
If two angles form vertical angles they are congruent.

6. 2. Angle Relationships Conjecture 3: Linear Pair Conjecture
If two angles form a linear pair then they are supplementary.

7. Vertical Angles are opposite one another. Vertical angles are congruent.
100°
100°

8. Lines l and m are parallel. l||m
Note the 4 angles that measure 120°.
120°
120° l
120°
120° m
Line n is a transversal. n

9. Lines l and m are parallel. l||m
There are 4 pairs of angles that are vertical.
There are many pairs of angles that are supplementary.
60°
120°
120°
60° l
60°
120°
120°
60° m
Line n is a transversal. n

10. 2. Angle Relationships Conjecture 4: Triangle Sum Conjecture
The sum of the angles of a triangle is 180°.

11. 5. Angle Relationships Conjecture 5: Parallel Line Conjecture
If two parallel lines are cut by a transversal then:
alternate interior angles are congruent,
alternate exterior angles are congruent, and
corresponding angles are congruent.

12. If two lines are intersected by a transversal and any of the angle pairs shown below are congruent, then the lines are parallel. This fact is used in the construction of parallel lines.

13. Ask them for the other angle pairs
5. Angle Relationships
How many angles are there? 1 2 8 3 4
Corresponding angles.
2 & 6
4 & 8
3 & 7
1 & 5 5 6
Alternate interior angles 7 8
4 & 5
3 & 6
Ask them for the other angle pairs
Alternate exterior angles
1 & 8
2 & 7

14. 5. Angle Relationships Conjecture 5: Parallel Line Conjecture
If two parallel lines are cut by a transversal then:
alternate interior angles are congruent,
alternate exterior angles are congruent, and
corresponding angles are congruent.

15. 1) Find the missing angle.?°
36°

16. 1) Find the missing angle.?°
36°
90 ° – 36 = 54°

17. 2) Find the missing angle.?°
64°

18. 2) Find the missing angle.?°
64°
90 ° – 64° = 26°

19. 5) Find the missing angle.
168° ?°

20. 5) Find the missing angle.
168° ?°
180° – 168° = 12°

21. 6) Find the missing angle.?°
58°

22. 6) Find the missing angle.?°
58°
180° – 58° = 122°

23. 7) Solve for x. 5x 4x
4x + 5x = 180
9x = 180
x = 20

24. 8) Solve for x.
3x + 20
2x + 10

25. 9) Lines l and m are parallel. l||m Find the missing angles.
42°
a ° c° b° l d° e° g° f° m

26. 9) Lines l and m are parallel. l||m Find the missing angles.
42°
138°
138°
42° l
42°
138°
138°
42° m

27. 10) Lines l and m are parallel. l||m Find the missing angles.
81°
a ° c° b° l d° e° g° f° m

28. 10) Lines l and m are parallel. l||m Find the missing angles.
81°
99°
99°
81° l
81°
99°
99°
81° m

29. 11) Find the missing angles.
70 °
70 ° b°
Hint: The 3 angles in a triangle sum to 180°.
d °
65 °

30. 11) Find the missing angles.
70 °
70 °
40°
Hint: The 3 angles in a triangle sum to 180°.
75 °
65 °

31. 12) Find the missing angles.
45 °
50 ° b°
Hint: The 3 angles in a triangle sum to 180°.
d °
75 °

32. 12) Find the missing angles.
45 °
50 °
85°
Hint: The 3 angles in a triangle sum to 180°.
20°
75 °

33. 13. Name the angles congruent to 3. 1, 5, 7
In the figure a || b.
13. Name the angles congruent to 3.
1, 5, 7
14. Name all the angles supplementary to 6.
1, 3, 5, 7
15. If m1 = 105° what is m3?
105°
16. If m5 = 120° what is m2?
60°