$A$ circle touches the axes at the points $(3, 0)$ and $(0, -3)$. The centre of the circle is

$A$ circle having its centre at the origin passes through the three vertices of an equilateral triangle,the length of whose median is $9$ units. Then,the equation of that circle is

If $(a, 1/a)$,$(b, 1/b)$,$(c, 1/c)$,and $(d, 1/d)$ are four distinct points on a circle of radius $4$ units,then $abcd$ is equal to

Through which of the following pairs of points does the circle $x^2 + y^2 - 12x + 1 = 0$ pass?

The equation of the circle concentric with the circle $x^2+y^2-6x-4y-12=0$ and touching the $Y$-axis is:

Find the centre and radius of the circle $2x^{2} + 2y^{2} - x = 0$.