Answer key for identifying acute, obtuse, and right angles in a geometry worksheet.

To identify the type of each angle, we look at how wide the opening is between the two lines (rays).

Here are the rules:
* Acute Angle: The angle is smaller than a corner of a square. It looks "sharp" or narrow. (Less than 90 degrees)
* Right Angle: The angle looks exactly like the corner of a square or a book. It forms an "L" shape. (Exactly 90 degrees)
* Obtuse Angle: The angle is wider than a corner of a square. It looks "open" or wide. (More than 90 degrees)

Let's go through the angles row by row, from left to right:

Row 1:
1. This angle is very wide open. -> obtuse
2. This angle is also wide open. -> obtuse
3. This angle is narrow and sharp. -> acute
4. This angle is very narrow. -> acute

Row 2:
5. This angle is narrow. -> acute
6. This angle is wide open. -> obtuse
7. This angle forms a perfect "L" shape. -> right
8. This angle is narrow. -> acute

Row 3:
9. This angle forms a perfect "L" shape. -> right
10. This is a straight line, which is the widest possible angle here. -> obtuse
11. This angle is narrow. -> acute
12. This angle is narrow. -> acute

Row 4:
13. This angle is wide open. -> obtuse
14. This angle is wide open. -> obtuse
15. This angle is narrow. -> acute
16. This angle is narrow. -> acute

Row 5:
17. This angle is wide open. -> obtuse
18. This angle is wide open. -> obtuse
19. This angle is narrow. -> acute
20. This is a straight line, which is wide. -> obtuse

Final Answer:
Row 1: obtuse, obtuse, acute, acute
Row 2: acute, obtuse, right, acute
Row 3: right, obtuse, acute, acute
Row 4: obtuse, obtuse, acute, acute
Row 5: obtuse, obtuse, acute, obtuse