column vector( 4,1) has been rotated to column vector (-1,4)which matrix carried out the transformation
+36916 cos 243 -sin 243
-sin243 -cos 243 Rotation is 242.928 clockwise ( I rounded to 243 degrees)
+36916 Seems I made that more difficult than necessary.....
rotate the vector 90 degree counter clockwise
cos 90 - sin 90
sin 90 cos 90 or : 0 -1
1 0
