1. 1-5 Angle Relationships What are: adjacent angles linear pairs
vertical angles
complementary angles supplementary angles
perpendicular lines

2. Adjacent angles
Adjacent angles are two angles that lie in the same plane and have a common vertex and a common side, but no common interior points. 1 2

3. Linear Pair
A linear pair is a pair of adjacent angles with noncommon sides that are opposite rays. 1 2

4. Definition
Two angles, , form a linear pair if and only if A, B, and C are collinear and D is not on A B C D

5. Name all the linear pairsF G H K J

6. Vertical Angles
Two angles are vertical angles if and only if their sides form two pairs of opposite rays.
OR…When two lines intersect, they form two pairs of vertical angles. 2 1 3 4

7. Definition
Complementary angles are two angles whose measures add up to 90° A B C D

8. Try it
Find the measures of 1 2 3
134°

9. Definition
Supplementary angles are two angles whose measures add up to 180° R S T U

10. Linear Pair Postulate
The angles in a linear pair are supplementary

11. What is the difference? Supplementary because it adds to 180°
AND
Linear pair because both angles are on the same line.

12. Complementary or Supplementary?
41°
49°
41°
139° P S
Angles can be complementary or supplementary regardless of their location.

13. find the measures of the angles that are complementary and supplementary to
90°− 64° = 26°
Supplementary
180°− 64° = 116°

14. Review
p. 46

15. Review
p. 47

16. Assignment 1-5
Page 51, 8-17,

17. Angle Relationships Day 2
What are perpendicular lines?
What can be assumed or not assumed in a drawing?

18. Perpendicular Lines
Lines, line segments or rays that form right angles are perpendicular. B A D C

19. B
Perpendicular Lines A C D
Perpendicular lines intersect to form four right angles.
Perpendicular lines intersect to form congruent adjacent angles.
Segments and rays can be perpendicular to lines or other line segments and rays.
The right angle symbol in the figure indicated that the lines are perpendicular.

20. To Assume or Not to Assume…
In the figure, do you think you would be justified in assuming that:
B, C, and E are collinear? A B C E F G
BE ll GD? D

21. Make a List…
Make a list of rules about what you think you can and cannot assume. A B C E F G

22. What can and cannot be assumed
You May Assume:
You May Not Assume
(unless marked):
Things that look straight are straight.
Exact measurements and relative sizes of figures.
Points shown on a line are collinear.
All points shown are coplanar.
Parallel or perpendicular lines.
Relative position of points are accurate (intersection, between-ness).
Congruence

23. To Assume or Not to Assume…
Point S is between R and T.
Points R,S, and T are collinear.
Point S is the midpoint of RT.
VY<TY R S T V W Y Z

24. Assignment 1-5 Day 2
Worksheet 1-5