sub 1 d sup 2 2x r sub 1 d 2x sup 2 r sub 1 sup 2 2r sub 1 d d sup 2 2xr sub 1 2xd x sup 2 b sup 2 r sub 1 cos 45 u00b0 sup 2 r sub 1 sup 2 2r sub 1 sup d d sup 2 2r sub 1 b r sub 1 cos 45 u00b0 2d b r sub 1 cos 45 u00b0 b sup 2 2br sub 1 cos 45 u00b0 r sub 1 cos 45 u00b0 sup 2 r sub 1 cos 45 u00b0 sup 2 r sub 1 sup 2 2r sub 1 d d sup 2 2r sub 1 b 2r sub 1 sup 2 cos 45 u00b0 2db 2dr sub 1 cos 45 u00b0 2br sub 1 cos 45 u00b0 r sub 1 cos 45 u00b0 sup 2 2r sub 1 b 2db 2br sub 1 cos 45 u00b0 r sub 1 sup 2 2r sub 1 d d sup 2 2r sub 1 sup 2 cos 45 u00b0 2dr sub 1 cos 45 u00b0 r sub 1 cos 45 u00b0 sup 2 r sub 1 cos 45 u00b0 sup 2 equ1 as r 2 is rotated about the point defined by the distance x from the center of the circle one side of the wheel shape is defined the other three sides are defined by relocating the point defined by the distance x from the circle in 90 u00b0 increments and rotating r 2 about each point the maximum radial deviation can vary from a value almost approaching a circle up.