Question

The line x=y touches a circle at the
point (1,1). If the circle also passes through
(1-3). Then It's radius is
passes through
x=y​

Answer 1

Answer:

Equation of circle can be written as

(x−1)

2

+(y−1)

2

+λ(x−y)=0

If passes through (1,3)

16+λ(4)=0⇒λ=−4

So (x−1)

2

+(y−1)

2

−4(x−y)=0

⇒x

2

+y

2

−6x+2y+2=0

⇒r=2

2