A. x2+y2-4x-6y+4=0

B. x2+y2+6x-8y+16=0

C. x2+y2-8x-6y+21=0

D. x2+y2-24x-10y+144=0

The condition that the circles x^{2}+y^{2}+2ax+2by+c=0, x^{2}+y^{2}+2bx+2ay+c=0 to touch each other is

The number of common tangents that can be drawn to the circles x^{2}+y^{2}=1 and x^{2}+y^{2}-2x-6y+6=0 is

The lines 2x-3y=5 and 3x-4y=7 are two diameters of a circle of area 154 sq unit. Then the equation of this circle is

The circle x^{2}+y^{2}-4x+4y-1=0 cuts the positive coordinate axes in A and B respectively. The equation to the diameter of the circle perpendicular to the chord AB is

If the equation of the circle cutting orthogonally the circles x^{2}+y^{2}-6x=0, x^{2}+y^{2}+4x+3y+1=0 and which has its centre on the line x+2y=5 is x^{2}+y^{2}-2ax-2by+c=0 then the descending order of a, b, c is