The length of the diameter of the circle $x^2+y^2-6x-8y=0$ is $...$ units.

The equation of the circle which touches the $X$-axis and $Y$-axis at the points $(1, 0)$ and $(0, 1)$ respectively is

$A$ circle passes through $(-2, 4)$ and touches the $y-$axis at $(0, 2).$ Which one of the following equations can represent a diameter of this circle?

The equation of the circle which passes through the points $(3, -2)$ and $(-2, 0)$ and whose centre lies on the line $2x - y = 3$ is:

In $\triangle ABC$,$\angle A = 90^{\circ}$ and the coordinates of points $B$ and $C$ are $(2, -4)$ and $(1, 5)$. Then the equation of the circumcircle of $\triangle ABC$ is

Find the radius and center of the circle $2x^2 + 2y^2 = 3x - 5y + 7$.