Find the radius and centre of the circle of the circle `x^(2) + y^(2) + 2x + 4y -1=0`.

Find the centre and radius of the circle x^(2) + y^(2) - 6x + 4y - 12 =0 .

Find the centre and radius of the circle x^(2) + y^(2) - 6x + 4y - 12 =0 .

Find the centre and radius of the circle x^(2) + y^(2) + 2x-4y-4=0

(i) Find the equation of a circle , which is concentric with the circle x^(2) + y^(2) - 6x + 12y + 15 = 0 and of double its radius. (ii) Find the equation of a circle , which is concentric with the circle x^(2) + y^(2) - 2x - 4y + 1 = 0 and whose radius is 5. (iii) Find the equation of the cricle concentric with x^(2) + y^(2) - 4x - 6y - 3 = 0 and which touches the y-axis. (iv) find the equation of a circle passing through the centre of the circle x^(2) + y^(2) + 8x + 10y - 7 = 0 and concentric with the circle 2x^(2) + 2y^(2) - 8x - 12y - 9 = 0 . (v) Find the equation of the circle concentric with the circle x^(2) + y^(2) + 4x - 8y - 6 = 0 and having radius double of its radius.

Find the centre and the radius of the circles 3x^(2) + 3y^(2) - 8x - 10y + 3 = 0

Find the centre and the radius of the circles 3x^(2) + 3y^(2) - 8x - 10y + 3 = 0

Find the centre and radius of the circle x^(2) + y^(2) + 6x -10y -2 =0

Find the centre and radius of the circle x^(2) + y^(2) + 6x -10y -2 =0

Find the locus of the centres of the circle which cut the circles x^(2)+y^(2)+4x-6y+9=0 and x^(2)+y^(2)+4x+6y+4=0 orthogonally