The document discusses angles and how to measure them. An angle is formed when two rays share an endpoint called the vertex. A protractor is used to measure angles by lining up the vertex with the 0 mark and reading the degree measure. There are three kinds of angles: acute angles measure less than 90 degrees, right angles measure exactly 90 degrees, and obtuse angles measure more than 90 degrees.

1. 8-2 Measuring and
Classifying Angles
Math Notes
Measurement and Geometry 2.1

2. Angle
An ANGLE is formed when two rays have the
SAME ENDPOINT, called the VERTEX.
BMN

3. Angle
An ANGLE is formed when two rays have the
SAME ENDPOINT, called the VERTEX.
BMN
. .
M first
N
ray

4. Angle
An ANGLE is formed when two rays have the
SAME ENDPOINT, called the VERTEX.
second B. BMN
ray
. .
M first
N
ray

5. Angle
An ANGLE is formed when two rays have the
SAME ENDPOINT, called the VERTEX.
second B. BMN
ray
. .
VERTEX
M first
N
ray

6. Angle
An ANGLE is formed when two rays have the
SAME ENDPOINT, called the VERTEX.
second B. BMN
ray
.
ANGLE
.
VERTEX
M first
N
ray

7. Review

8. Review
. .
S first
ray T

9. Review
R
.
second
ray
. .
S first
ray T

10. Review
R
.
second
ray
. .
VERTEX S first
ray T

11. Review
R
.
second
ray
ANGLE
. .
VERTEX S first
ray T

12. Review
R
. RST
second
ray
ANGLE
. .
VERTEX S first
ray T

13. Protractor
Used to measure angles.

14. Protractor
Used to measure angles.

15. How to use a Protractor

16. How to use a Protractor
.
R
. .
S T

17. How to use a Protractor
.
R
. .
S T

18. How to use a Protractor
.
R
. .
S T
Line up the vertex with this mark.

19. How to use a Protractor
.
R
. .
S T
Line up the vertex with this mark.

20. How to use a Protractor
.
R
. .
S T
Line up the vertex with this mark.

21. How to use a Protractor
Start with 0 degrees
and measure
.
R
. .
S T
Line up the vertex with this mark.

22. How to use a Protractor
Start with 0 degrees
and measure
.
R
. .
S T
Line up the vertex with this mark.

23. How to use a Protractor
Start with 0 degrees
and measure
.
R
. .
S T
Line up the vertex with this mark.

24. How to use a Protractor
Start with 0 degrees
and measure
.
R
120˚
. .
S T
Line up the vertex with this mark.

25. 3 Kinds of Angles

26. 3 Kinds of Angles
ACUTE angles measure LESS than 90˚

27. 3 Kinds of Angles
ACUTE angles measure LESS than 90˚
RIGHT angles measure exactly 90˚

28. 3 Kinds of Angles
ACUTE angles measure LESS than 90˚
RIGHT angles measure exactly 90˚
OBTUSE angles measure MORE than 90˚

29. 3 Kinds of Angles
ACUTE angles measure LESS than 90˚
RIGHT angles measure exactly 90˚
OBTUSE angles measure MORE than 90˚

30. 3 Kinds of Angles
ACUTE angles measure LESS than 90˚
RIGHT angles measure exactly 90˚
OBTUSE angles measure MORE than 90˚
90˚

31. 3 Kinds of Angles
ACUTE angles measure LESS than 90˚
RIGHT angles measure exactly 90˚
OBTUSE angles measure MORE than 90˚
90˚
Right Angle

32. 3 Kinds of Angles
ACUTE angles measure LESS than 90˚
RIGHT angles measure exactly 90˚
OBTUSE angles measure MORE than 90˚
90˚
Right Angle

33. 3 Kinds of Angles
ACUTE angles measure LESS than 90˚
RIGHT angles measure exactly 90˚
OBTUSE angles measure MORE than 90˚
LESS
than
90˚
90˚
Right Angle

34. 3 Kinds of Angles
ACUTE angles measure LESS than 90˚
RIGHT angles measure exactly 90˚
OBTUSE angles measure MORE than 90˚
LESS
than
90˚
90˚
Acute Angle Right Angle

35. 3 Kinds of Angles
ACUTE angles measure LESS than 90˚
RIGHT angles measure exactly 90˚
OBTUSE angles measure MORE than 90˚
LESS
than
90˚
90˚
Acute Angle Right Angle

36. 3 Kinds of Angles
ACUTE angles measure LESS than 90˚
RIGHT angles measure exactly 90˚
OBTUSE angles measure MORE than 90˚
LESS MORE
than than
90˚ 90˚
90˚
Acute Angle Right Angle

37. 3 Kinds of Angles
ACUTE angles measure LESS than 90˚
RIGHT angles measure exactly 90˚
OBTUSE angles measure MORE than 90˚
LESS MORE
than than
90˚ 90˚
90˚
Acute Angle Right Angle Obtuse Angle