Math worksheet for identifying acute, obtuse, and right angles.

To solve the problem of identifying each angle as acute, obtuse, or right, we need to understand the definitions of these types of angles:

1. Acute Angle: An angle that measures less than 90 degrees.
2. Right Angle: An angle that measures exactly 90 degrees.
3. Obtuse Angle: An angle that measures more than 90 degrees but less than 180 degrees.

Now, let's analyze each angle in the image step by step:

Row 1:

1. Acute
2. Right
3. Obtuse
4. Obtuse

Row 2:

5. Obtuse
6. Acute
7. Acute
8. Acute

Row 3:

9. Acute
10. Obtuse
11. Acute
12. Obtuse

Row 4:

13. Acute
14. Obtuse
15. Obtuse
16. Obtuse

Row 5:

17. Obtuse
18. Right
19. Obtuse
20. Straight (Note: This is not one of the options, but it's important to recognize it)

Final Answer:

- Acute: 1, 6, 7, 9, 10, 13, 18, 19
- Right: 2, 18
- Obtuse: 3, 4, 5, 8, 11, 12, 14, 15, 16, 17, 20

So, the solution is:

\[
\boxed{
\text{Acute: 1, 6, 7, 9, 10, 13, 18, 19; Right: 2, 18; Obtuse: 3, 4, 5, 8, 11, 12, 14, 15, 16, 17, 20}
}
\]