All _____of a circle are equal in measure.

Options

A. Sectors
B. Radii
C. Segments
D. Chords

Answer

To solve the question "All _____ of a circle are equal in measure," we need to identify the term that fits in the blank.

### Step-by-Step Solution:

1. **Understanding the Circle**:
- A circle is defined as the set of all points that are at a fixed distance (radius) from a central point (center).
- The fixed distance from the center to any point on the circle is called the radius.

2. **Identifying Equal Parts**:
- We need to determine which parts of the circle are equal in measure.
- The options to consider might include: sectors, segments, chords, or radii.

3. **Analyzing the Options**:
- **Sectors**: These are parts of the circle formed by two radii and the arc between them. They are not necessarily equal.
- **Segments**: These are regions formed by a chord and the arc it subtends. They can vary in size.
- **Chords**: These are line segments whose endpoints lie on the circle. Chords can be of different lengths.
- **Radii**: These are the line segments from the center of the circle to any point on the circle.

4. **Conclusion**:
- Since all radii of a circle are the same length (equal distance from the center to the edge), the correct term to fill in the blank is "radii".

### Final Answer:
All **radii** of a circle are equal in measure.