If 2x−4y=9 and  6x−12y+7=0 are parallel tangents to circle, then radius of the circle, is

The equations of two tangents are 2x−4y−9=1 and 6x-12y+7=0. Clearly, these are parallel. The distance between these lines is  −9−74+16=1735             Using :d=c1−c2a2+b2∴   Radius of the circle =12×1735=1765