Answer:
A. The distance from any point in the circle to the origin
Explanation:
The distance formula tells you that the distance (d) is related to the coordinates of two points (x1, y1) and (x2, y2) by ...
d² = (x2 -x1)² +(y2 -y1)²
For points (x, y) on the circle and (0, 0) at the origin, this becomes ...
d² = (x -0)² +(y -0)²
If we want the distance to the point (x, y) to be equal to the radius of the circle, this becomes ...
x² +y² = r² . . . . . . the standard equation of a circle centered at the origin