The equations of the circles which touch both the
axes and the line x=a are
x2+y2±ax±ay+a24=0
x2+y2+ax±ay+a24=0
x2+y2−ax±ay+a24=0
none of these
Since the circle touches both the axes and the line
x =a. Therefore, coordinates of its centre are (a/2,±a/2) and
radius a/2.
Hence, the required circles are
x−a22+y∓a22=a22⇒x2+y2−ax±ay+a24=0