Question

point b is the image of point a when a is rotated 90° counterclockwise around the origin.

point b must be the same
from the origin as point a.

Explanation:

Rotation is a rigid transformation, which preserves the distance between the rotated point and the center of rotation (the origin here). This means the distance from the origin to point A is identical to the distance from the origin to point B.

Answer:

distance