Find the equation of a circle passing through the point (7, 3) having radius 3 units and whose centre lies on the line y = x – 1.
Given that circle passes through the point A(7,3) and its radius is 3
Therefore centre of the circle is C(h,h-1)
Now, radius of the circle is AC=3
(h-7)2+(h-1-3)2=32
2h2-22h+56=0
h2-11h+28=0
(h-4)(h-7)=0
h=4 or 7
If the centre of the circle is C(4,3)⇒(x-4)2+(y-3)2=9⇒x2+y2-8x-6y+16=0
If the centre is C(7,6)⇒(x-7)2+(y-6)2=9⇒x2+y2-14x-12y+76=0