By definition:
- A circle is a round-shaped 2-dimensional figure that consists of a series of points located at the same distance from a point located in the middle of the circle called "Center".
- Therefore, the center of a circle is that point located in the middle of the circle.
- The radius of a circle is half its diameter. It is a segment that goes from the center of the circle to any point on the circumference of the circle.
Hence, the answers are:
1. Center.
2. Point.
3. Point.
