AP EAMCET Engineering 18 Sep 2020 Shift 1 Paper

The point of reflection of (m,n) on the line
y−x=0 is (n,m), so equation of circle having centre (n,m) and let radius r is
(x−n)2+(y−m)2=r2.....(i)
∵ Circle (i) touches the X− axis, so r=m
So, equation of required circle is
(x−n)2+(y−m)2=m2
or x2+y2−2nx−2my+n2=0