Here's the question you clicked on:
DLS
If 2x-4y-9=0 & 6x-12y+7=0 are tangents to same circle then R=?
yahan par inhone 2r=|P1-P2| kiya hai why did they subtract:/
yeah i remember doing it that way. But I'm not sure why.... lemme think..
Hmm.. Not sure if this way works! 2x-4y-9=0 & 6x-12y+7=0 = tangents to the same circle. That have the same slope => perpendicular distance between the two lines is the diameter of the circle. Half of the diameter is the radius :\ I think this is not a smart way to solve your problem though :(
as @Callisto rightly stated..the lines are parallel, distance between them gives diameter, half of diameter is radius! voila !