use the perpendicular distance formula to find the distance( radius) from the line to the centre (let the centre be something like (a,b)...) then use it again to find the distance (radius) from the line x=0 and from line y=o. you will then have three euations and three unknown... a,b and r. use subsitution to figure out these unknownss... hope it helps...(btw...I havnt tried thid method for your question..so i hope it works...)