Rotation means rotating a shape through certain angle.
The shape can be one Dimensional , 2 dimensional or 3 Dimensional.
Angle of rotation lies between 0 degrees to 360 degrees.
The point (x,y) lies in two Dimensional coordinate system.
Since point (x,y) is rotated and we are getting new coordinate as (y,-x).
The point (x,y) lies in first quadrant and the point (y,-x) lies in fourth quadrant.
Also,Distance of x-coordinate from X-axis=Distance of y coordinate from Y-axis
,Distance of y-coordinate from Y-axis=Distance of x coordinate from X-axis
So, Either the shape is rotated through anticlockwise motion through an angle of 270 degrees or through an angle of 90 degrees in clockwise motion.