If the length of the tangets from two points A, B to a circles are 6, 7 respectively. If A, B are conjugate points then AB=

The length of the tangent from a point on the circle x²+y²+2gx+2fy+c=0 to the circle x²+y²+2gx+2fy+c^’=0 is

The normal of the circle(x-2)²+(y-1)²=16 which bisects the chord cut off by the line x-2y-3=0 is

The length of the common chord of the circles (x-a)²+(y-b)²=c² and (x-b)²+(y-a)²=c²

The external centre of similitude of the two circles x²+y²-2x-6y+9=0, x²+y²=4 is

The longest distance from (-3, 2) to the circles x²+y²-2x+2y+1=0 is

If the equation of the circle passing through the origin and the points of intersection of the two circles x²+y²-4x-6y-3=0, x²+y²+4x-2y-4=0 is x²+y²+2ax+2by+c=0  then the ascending order of a, b,c is

The circle passing through the points (1, t), (t, 1) and (t, t) for all values of t passes through the point

The equation of the circle passing through the points of intersection of the circles x²+y²+2x+3y+1=0,  x²+y²+4x+3y+2=0 and through the point (-1, 2)is

The two circles x²+y²+2ax+2by+c=0 and x²+y²+2bx+2ay+c=0 have three real common tangents, then