Prove that the centres of the three circles `x^(2) + y^(2) - 2x + 6y + 1 = 0, x^(2) + y^(2) + 4x - 12y + 9 = 0` and `x^(2) + y^(2) - 16 = 0` are collinear.

Prove that the centres of the circle x^(2) + y^(2) - 4x - 2y + 4 = 0, x^(2) + y^(2) - 2x - 4y + 1 = 0 and x^(2) + y^(2) + 2x - 8y + 1 = 0 are collinear. More over prove that their radii are in geometric pregression.

Prove that the centres of the three circles x^2 + y^2 - 4x – 6y – 12 = 0,x^2+y^2 + 2x + 4y -5 = 0 and x^2 + y^2 - 10x – 16y +7 = 0 are collinear.

The radical centre of the circles x^(2) + y^(2)- 2x + 6y = 0 , x^(2) + y^(2) - 4x - 2y + 6 = 0 , x^(2) + y^(2) - 12x + 12y + 30 = 0 is

Prove that the centres of the three circles x^(2)+y^(2)-4x6y12=0,x^(2)+y^(2)+2x+4y-5=0 and x^(2)+y^(2)-10x16y+7=0 are collinear.

Prove that the centres of the three circles : x^2 + y^2 -4x-6y-14=0, x^2 + y^2+ 2x+4y-5=0 and x^2 + y^2-10x -16y + 7 = 0 are collinear.

The circles x^2 + y^2 + 6x + 6y = 0 and x^2 + y^2 - 12x - 12y = 0

The equation of the circle which cuts orthogonally the three circles x^(2) + y^(2) + 4x + 2y + 1 = 0 , 2x^(2) + 2y^(2) + 8x + 6y - 3 = 0 , x^(2) + y^(2) + 6x - 2y - 3 = 0 is

Find the external centre of similitude for the circles x^(2) + y^(2) - 2x - 6y + 9 =0 and x^(2) + y^(2) = 4

Radii of circles x^(2) + y^(2) = 1, x^(2) + y^(2) - 2x - 6y= 6 and x^(2) + y^(2) - 4x - 12y = 9 are in

The centres of the three circles x^(2)+y^(2)-10x+9=0,x^(2)+y^(2)-6x+2y+1=0,x^(2)+y^(2)-9x-4y+2=0