2. Classifying Angles
Mrs. Delana Smith

3. Today’s Objective
By the end of our lesson, you will be able to classify angles as acute, obtuse, or right.
GLE Understand and use the properties of lines, segments, angles, polygons, and circles.
√ Classify angles and triangles as obtuse, acute, or right.
SPI Identify acute, obtuse, or right angles in 2-dimensional shapes.

4. What is an Angle?
An angle is made up of two rays that share a common endpoint, called a vertex.
common endpoint, or vertex

5. Naming Angles Similar to naming lines, segments, and rays.
There are two ways we can name angles—1: using vertex 2: using all three points
Read as “Angle B” or
“Angle ABC” or
“Angle CBA”
Write as:
B ABC CBA A B C

6. Measuring Angles
We measure angles in degrees using a protractor. Angles have measures from 1°-180°.
This angle measures 65°.

7. Types of Angles
Right
Acute
Obtuse
Straight

8. The box tells you it is a right angle!
Right Angles
Right angles measure EXACTLY 90°.
The box tells you it is a right angle! X X

9. Acute Angles
Acute angles have measures from 1°-89°.

10. Obtuse Angles
Obtuse angles have measures from 91°-179°.

11. Straight Angles
Straight angles have measures of EXACTLY 180°. H

12. Watch Me Classify This Angle…

13. Watch Me Classify This Angle…
GPD ? P G D

14. You Help Me…

15. Let Me Help You…

16. You Try One…

17. Acute, Obtuse, or right?
N L
V E
NLE ?

18. Another…

19. Another…

20. One Last Example
W M
Z K
WZK ?