4π(3+√2)
8π(2-√2)
4π(2-√2)
8π(3-2√2)
The correct option is B
8π(2-√2)
Equation of the circle is (x-1)²+(y-2)²+λ(x-y+1)=0
⇒x²+y²+x(λ-2)+y(-4-λ)+(5+λ)=0
As circle touches x axis then g²-c=0
(λ-2)²/4 = (5+λ)
λ²+4-4λ=20+4λ
λ²-8λ-16=0
λ=8±√128/2
λ=4±4√2
Radius=√((-4-λ)²/4-(5+λ))
Put λ and get least radius