`0^(@)` .........acute angle .........`90^(@) lt` obtuse angle `lt 180^(@)`.

Answer

To solve the problem of identifying the types of angles based on the given criteria, we can break it down into steps:

### Step-by-Step Solution:

1. **Understanding Angles**:
- An angle is formed by two rays originating from a common point (the vertex).
- Angles can be classified based on their measures.

2. **Identifying Acute Angles**:
- An acute angle is defined as an angle that measures greater than 0 degrees but less than 90 degrees (0° < angle < 90°).
- This means any angle in this range is considered acute.

3. **Identifying Obtuse Angles**:
- An obtuse angle is defined as an angle that measures greater than 90 degrees but less than 180 degrees (90° < angle < 180°).
- Thus, any angle that falls within this range is classified as obtuse.

4. **Conclusion**:
- Based on the definitions:
- An angle that is greater than 0 degrees and less than 90 degrees is an acute angle.
- An angle that is greater than 90 degrees and less than 180 degrees is an obtuse angle.

### Summary of the Angle Ranges:
- **Acute Angle**: 0° < angle < 90°
- **Obtuse Angle**: 90° < angle < 180°