A. 9x2+80xy-75y2-500x-200y+2900=0

B. 9x2-15y2-6x+60y-51=0

C. 16x2+20xy-5y2-36x+90y-261=0

D. 3x2-10xy+3y2=0

The equation of one tangent to the circle with Centre(2,-1) from the origin is 3x + y = 0, then the equation of the other tangent through the origin is

The equation to the circle which is such that the lengths of the tangents to it from the points (1,0), (2,0) and (3,2)are 1,√7, √2, respectively is

The locus of the centre of the circles which touché both the circles x^{2}+y^{2}=a^{2} and x^{2}+y^{2}=4ax externally has the equation

The locus of the centre of the circle which cuts the circles x^{2}+y^{2}+4x-6y+9=0 and x^{2}+y^{2}-4x+6y+4=0 orthogonally is

A circle touches the x-axis and also touches the circle with centre at (0, 3) and radius 2. The locus of the centre of the circle is