In the plane Cartesian coordinate system, when the point a (4,2) is rotated 90 ° counterclockwise around the origin, the coordinate of the corresponding point a 'is____

In the plane Cartesian coordinate system, when the point a (4,2) is rotated 90 ° counterclockwise around the origin, the coordinate of the corresponding point a 'is____

(2,-4)

After the point P (3, - 4) is rotated 90 ° clockwise around the origin, the coordinates of point q are obtained

（-4,-3）

Let p be a moving point on the circle M: (X-5) 2 + (Y-5) 2 = 1, whose symmetric point about a (9,0) is Q. rotate P 90 ° counterclockwise around the origin to the point s,
Find the maximum value of | sq |

2√106±√2