Answer:
(-1, -1)
Explanation:
(1, -1) is a point in Quadrant IV whose radius (length of the ray from (0, 0) to the circle) is √2 (according to the Pythagorean Theorem).
If we rotate this ray 90° clockwise, we'll end up in Quadrant III, with the ray forming a 45° angle with each the x-axis and the y-axis.
This new point will be (-1, -1).