Equations of normal are
y+2x=11+77...(i)
2y+x=211+67...(ii)
Now the center of the circle is point of intersection of the normals i.e. solving (i)&(ii), we get the point of intersection as
(387,11+357)≡(h,k)
The equation of tangent is 11y−3x=3577+11
The radius will be perpendicular distance of tangent from center
i.e. r=11+9∣11387−3(11+357)−3577−11∣=457
Hence (5h−8k)2+5r2=816