If 2x-4y-9=0 & 6x-12y+7=0
are tangents to same circle then R=?

Question

If 2x-4y-9=0 & 6x-12y+7=0
are tangents to same circle then R=?

dls · Answer

@ParthKohli @rajathsbhat

dls · Answer

yahan par inhone 2r=|P1-P2| kiya hai why did they subtract:/

dls · Answer

|dw:1357385377449:dw|

anonymous · Answer

yeah i remember doing it that way. But I'm not sure why....
lemme think..

callisto · Answer

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 :(

shubhamsrg · Answer

as @Callisto rightly stated..the lines are parallel, distance between them gives diameter, half of diameter is radius! voila !