−ax+bxy=k =ax2−cy2+2ax−2ay−2bxy=k Above equation is circle ⇒a=−c and b=0 ax2+ay2+2ax−2ay=k ⇒x2+y2+2x−2y=λ‌‌[λ=‌
k
a
] Passes through (2,5) 4+25+4−10=λ⇒λ=23 Circle ≡x2+y2+2x−2y−23=0 Centre (−1,1)r=√(−1)2+12+23=5 Shortest distance of (11,6)=√122+52−5 =13−5 =8