When the sum of the measures of two angles is that of a straight angle and if one of them is acute then the other should be__________.

Answer

To solve the question, we need to understand the properties of angles, particularly the relationship between acute and obtuse angles.

### Step-by-Step Solution:

1. **Understanding the Definition of Angles**:
- An **acute angle** is an angle that measures less than 90 degrees.
- An **obtuse angle** is an angle that measures more than 90 degrees but less than 180 degrees.
- A **straight angle** measures exactly 180 degrees.

2. **Given Information**:
- The sum of the measures of two angles is equal to that of a straight angle, which is 180 degrees.
- One of the angles is acute.

3. **Setting Up the Equation**:
- Let’s denote the acute angle as \( A \) and the other angle as \( B \).
- According to the problem, we have:
\[ A + B = 180^\circ \]

4. **Analyzing the Acute Angle**:
- Since \( A \) is an acute angle, we know:
\[ A < 90^\circ \]

5. **Finding the Measure of the Other Angle**:
- To find angle \( B \), we can rearrange the equation:
\[ B = 180^\circ - A \]
- Since \( A < 90^\circ \), we can substitute this into the equation:
\[ B = 180^\circ - A > 180^\circ - 90^\circ = 90^\circ \]
- This means that angle \( B \) must be greater than 90 degrees.

6. **Conclusion**:
- Since angle \( B \) is greater than 90 degrees, it is classified as an **obtuse angle**.

### Final Answer:
If one of the angles is acute, then the other should be **obtuse**.