Q.

Circle(s) touching x-axis at a distance 3 from the origin and having an intercept of length 27 on y-axis is (are)                     [2013]

1 x2+y2-6x+8y+9=0  
2 x2+y2-6x+7y+9=0  
3 x2+y2-6x-8y+9=0  
4 x2+y2-6x-7y+9=0  

Ans.

(1, 3)

Here, there are two possibilities for the given circle as shown in the figure.

 The equations of circles can be

(x-3)2+(y-4)2=42  or  (x-3)2+(y+4)2=42

x2+y2-6x-8y+9=0  or  x2+y2-6x+8y+9=0