Which of the following is NOT a property of a unit circle?

The correct answer identifies that all points on a unit circle are not at a distance of pi from the center. A unit circle is defined specifically as a circle with a radius of 1, centered at the origin (0,0) of the coordinate plane. This means that the distance from the center to any point on the circle is precisely 1, not pi.

The distance of pi is unrelated to the definition of a unit circle. In fact, pi is the circumference of a unit circle, which is calculated as 2π times the radius. Since the radius is 1, the circumference is simply 2π. Thus, the claim that all points on the circle are at a distance of pi is incorrect.

The other properties mentioned are accurate: a unit circle indeed has its center at the origin, maintains a radius of 1, and exists within the coordinate plane, making them all valid descriptions of a unit circle.