Which of the following equations represents a cirlce? If so, determine its centre and radius
`x^2 + y^2 - 12x + 6y + 45 = 0`.

Find the centre and radius of the circle : x^2 + y^2- 4x- 8y- 45 = 0 .

Find the equations of the following curves in cartesian form. Wherever the curve is a circle, find its centre and radius : x= at^2, y=2at .

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

Find the centre and radius of the circle : x^2 + y^2- 8x+ 10y- 12 = 0 .

Find the centre and radius of the circle : x^2 + y^2+ 8x + 10y- 8 =0 .

In the following, find the centre and radius of the circles.:- x^2 + y^2 -4x -8y -45 = 0

In the following, find the centre and radius of the circles.:- x^2 + y^2 -8x + 10y - 12 = 0

In the following, find the centre and radius of the circles.:- 2x^2 + 2y^2 -x = 0