1.

The equation of a circle which touches the line y = x at (1 , 1) and having y = x -3 as a normal, isA. `4x^(2)+4y^(2)-20x+4y+8=0`B. `x^(2)+y^(2)-2x+4y+8=0`C. `x^(2)+y^(2)-10x-4y+8=0`D. none of these

Answer» Correct Answer - A
The equation of the family of circles is
`(x-1)^(2)+(y-1)^(2)+lambda(x-y)=0` ...(i)
Its centre lies on y=x-3.
`:. 1+(lambda)/(2)=1-(lambda)/(2)-3 rArr lambda = - 3`
Putting `lambda = -3` in (i), we obtain
`x^(2)+y^(2)-5x+y+2=0`


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